Check information. It is necessary to check the accuracy of the facts and reliability of the information presented in this article. On the talk page there is a discussion on the topic: Doubts regarding terminology. Chemical formula ... Wikipedia
A chemical formula reflects information about the composition and structure of substances using chemical symbols, numbers and dividing symbols of brackets. Currently, the following types of chemical formulas are distinguished: The simplest formula. Can be obtained by experienced... ... Wikipedia
A chemical formula reflects information about the composition and structure of substances using chemical symbols, numbers and dividing symbols of brackets. Currently, the following types of chemical formulas are distinguished: The simplest formula. Can be obtained by experienced... ... Wikipedia
A chemical formula reflects information about the composition and structure of substances using chemical symbols, numbers and dividing symbols of brackets. Currently, the following types of chemical formulas are distinguished: The simplest formula. Can be obtained by experienced... ... Wikipedia
A chemical formula reflects information about the composition and structure of substances using chemical symbols, numbers and dividing symbols of brackets. Currently, the following types of chemical formulas are distinguished: The simplest formula. Can be obtained by experienced... ... Wikipedia
Main article: Inorganic compounds List of inorganic compounds by element informational list of inorganic compounds presented in alphabetical order (by formula) for each substance, hydrogen acids of the elements (if ... ... Wikipedia
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A chemical equation (equation of a chemical reaction) is a conventional representation of a chemical reaction using chemical formulas, numerical coefficients and mathematical symbols. The equation of a chemical reaction gives qualitative and quantitative... ... Wikipedia
Chemical software computer programs, used in the field of chemistry. Contents 1 Chemical editors 2 Platforms 3 Literature ... Wikipedia
Books
- Japanese-English-Russian dictionary for installation of industrial equipment. About 8,000 terms, Popova I.S.. The dictionary is intended for a wide range of users and primarily for translators and technical specialists involved in the supply and implementation of industrial equipment from Japan or...
- A brief dictionary of biochemical terms, Kunizhev S.M.. The dictionary is intended for students of chemical and biological specialties at universities studying a course in general biochemistry, ecology and fundamentals of biotechnology, and can also be used in ...
Cheat sheet with formulas in physics for the Unified State Exam
and more (may be needed for grades 7, 8, 9, 10 and 11).
First, a picture that can be printed in a compact form.
Mechanics
- Pressure P=F/S
- Density ρ=m/V
- Pressure at liquid depth P=ρ∙g∙h
- Gravity Ft=mg
- 5. Archimedean force Fa=ρ f ∙g∙Vt
- Equation of motion for uniformly accelerated motion
X=X 0 + υ 0 ∙t+(a∙t 2)/2 S=( υ 2 -υ 0 2) /2a S=( υ +υ 0) ∙t /2
- Velocity equation for uniformly accelerated motion υ =υ 0 +a∙t
- Acceleration a=( υ -υ 0)/t
- Circular speed υ =2πR/T
- Centripetal acceleration a= υ 2/R
- Relationship between period and frequency ν=1/T=ω/2π
- Newton's II law F=ma
- Hooke's law Fy=-kx
- Law of Gravity F=G∙M∙m/R 2
- Weight of a body moving with acceleration a P=m(g+a)
- Weight of a body moving with acceleration а↓ Р=m(g-a)
- Friction force Ftr=µN
- Body momentum p=m υ
- Force impulse Ft=∆p
- Moment of force M=F∙ℓ
- Potential energy of a body raised above the ground Ep=mgh
- Potential energy of an elastically deformed body Ep=kx 2 /2
- Kinetic energy of the body Ek=m υ 2 /2
- Work A=F∙S∙cosα
- Power N=A/t=F∙ υ
- Efficiency η=Ap/Az
- Oscillation period of a mathematical pendulum T=2π√ℓ/g
- Oscillation period of a spring pendulum T=2 π √m/k
- Equation of harmonic vibrations Х=Хmax∙cos ωt
- Relationship between wavelength, its speed and period λ= υ T
Molecular physics and thermodynamics
- Amount of substance ν=N/Na
- Molar mass M=m/ν
- Wed. kin. energy of monatomic gas molecules Ek=3/2∙kT
- Basic MKT equation P=nkT=1/3nm 0 υ 2
- Gay-Lussac's law (isobaric process) V/T =const
- Charles's law (isochoric process) P/T =const
- Relative humidity φ=P/P 0 ∙100%
- Int. energy ideal. monatomic gas U=3/2∙M/µ∙RT
- Gas work A=P∙ΔV
- Boyle–Mariotte law (isothermal process) PV=const
- Amount of heat during heating Q=Cm(T 2 -T 1)
- Amount of heat during melting Q=λm
- Amount of heat during vaporization Q=Lm
- Amount of heat during fuel combustion Q=qm
- Equation of state of an ideal gas PV=m/M∙RT
- First law of thermodynamics ΔU=A+Q
- Efficiency of heat engines η= (Q 1 - Q 2)/ Q 1
- Efficiency is ideal. engines (Carnot cycle) η= (T 1 - T 2)/ T 1
Electrostatics and electrodynamics - formulas in physics
- Coulomb's law F=k∙q 1 ∙q 2 /R 2
- Tension electric field E=F/q
- Electrical tension point charge field E=k∙q/R 2
- Surface charge density σ = q/S
- Electrical tension fields of an infinite plane E=2πkσ
- Dielectric constant ε=E 0 /E
- Potential energy interaction. charges W= k∙q 1 q 2 /R
- Potential φ=W/q
- Point charge potential φ=k∙q/R
- Voltage U=A/q
- For a uniform electric field U=E∙d
- Electric capacity C=q/U
- Electric capacity of a flat capacitor C=S∙ ε ∙ε 0 /d
- Energy of a charged capacitor W=qU/2=q²/2С=CU²/2
- Current strength I=q/t
- Conductor resistance R=ρ∙ℓ/S
- Ohm's law for the circuit section I=U/R
- Laws of the last. connections I 1 =I 2 =I, U 1 +U 2 =U, R 1 +R 2 =R
- Laws parallel. conn. U 1 =U 2 =U, I 1 +I 2 =I, 1/R 1 +1/R 2 =1/R
- Electric current power P=I∙U
- Joule-Lenz law Q=I 2 Rt
- Ohm's law for a complete circuit I=ε/(R+r)
- Short circuit current (R=0) I=ε/r
- Magnetic induction vector B=Fmax/ℓ∙I
- Ampere power Fa=IBℓsin α
- Lorentz force Fl=Bqυsin α
- Magnetic flux Ф=BSсos α Ф=LI
- Law of electromagnetic induction Ei=ΔФ/Δt
- Induction emf in a moving conductor Ei=Вℓ υ sinα
- Self-induction EMF Esi=-L∙ΔI/Δt
- Energy magnetic field coils Wm=LI 2 /2
- Oscillation period no. circuit T=2π ∙√LC
- Inductive reactance X L =ωL=2πLν
- Capacitance Xc=1/ωC
- Effective current value Id=Imax/√2,
- Effective voltage value Ud=Umax/√2
- Impedance Z=√(Xc-X L) 2 +R 2
Optics
- Law of light refraction n 21 =n 2 /n 1 = υ 1 / υ 2
- Refractive index n 21 =sin α/sin γ
- Thin lens formula 1/F=1/d + 1/f
- Lens optical power D=1/F
- max interference: Δd=kλ,
- min interference: Δd=(2k+1)λ/2
- Differential grid d∙sin φ=k λ
Quantum physics
- Einstein's Physics for the photoelectric effect hν=Aout+Ek, Ek=U z e
- Red border of the photoelectric effect ν k = Aout/h
- Photon momentum P=mc=h/ λ=E/s
Physics atomic nucleus
- Law of radioactive decay N=N 0 ∙2 - t / T
- Binding energy of atomic nuclei
Instructions
The electrons in an atom occupy vacant orbitals in a sequence called the scale: 1s/2s, 2p/3s, 3p/4s, 3d, 4p/5s, 4d, 5p/6s, 4d, 5d, 6p/7s, 5f, 6d, 7p. An orbital can contain two electrons with opposite spins - directions of rotation.
The structure of electron shells is expressed using graphical electronic formulas. Use a matrix to write the formula. One or two electrons with opposite spins can be located in one cell. Electrons are represented by arrows. The matrix clearly shows that two electrons can be located in the s orbital, 6 in the p orbital, 10 in the d orbital, and -14 in the f orbital.
Write down the serial number and symbol of the element next to the matrix. In accordance with the energy scale, fill the 1s, 2s, 2p, 3s, 3p, 4s levels in succession, writing two electrons per cell. You get 2+2+6+2+6+2=20 electrons. These levels are completely filled.
You still have five electrons left and an unfilled 3d level. Arrange the electrons in the d-sublevel cells, starting from the left. Place electrons with the same spins in the cells, one at a time. If all the cells are filled, starting from the left, add a second electron with the opposite spin. Manganese has five d electrons, one in each cell.
Electron graphic formulas clearly show the number of unpaired electrons that determine valence.
Please note
Remember that chemistry is a science of exceptions. In atoms of side subgroups of the Periodic Table, electron “leakage” occurs. For example, in chromium with atomic number 24, one of the electrons from the 4s level goes to the d-level cell. Molybdenum, niobium, etc. have a similar effect. In addition, there is the concept of an excited state of an atom, when paired electrons are paired and transferred to neighboring orbitals. Therefore, when compiling electronic graphic formulas for the elements of the fifth and subsequent periods of the secondary subgroup, check the reference book.
Sources:
- how to write the electronic formula of a chemical element
Electrons are part of atoms. And complex substances, in turn, are made up of these atoms (atoms form elements) and share electrons among themselves. The oxidation state shows which atom took how many electrons for itself, and which gave away how many. This indicator is possible.
You will need
- School textbook on chemistry grades 8-9 by any author, periodic table, table of electronegativity of elements (printed in school textbooks on chemistry).
Instructions
To begin with, it is necessary to indicate that degree is a concept that takes connections for, that is, not going deep into the structure. If the element is in a free state, then this is the simplest case - a simple substance is formed, which means its oxidation state is zero. For example, hydrogen, oxygen, nitrogen, fluorine, etc.
IN complex substances this is not the case: electrons are not evenly distributed between atoms, and it is the oxidation state that helps determine the number of electrons given or received. The oxidation state can be positive or negative. When positive, electrons are given away; when negative, electrons are received. Some elements retain their oxidation state in various compounds, but many do not differ in this feature. One important rule to remember is that the sum of oxidation states is always zero. The simplest example is CO gas: knowing that the oxidation state of oxygen in the vast majority of cases is -2 and using the above rule, you can calculate the oxidation state for C. In sum with -2, zero gives only +2, which means the oxidation state of carbon is +2. Let’s complicate the problem and take CO2 gas for calculations: the oxidation state of oxygen still remains -2, but in this case there are two molecules. Therefore, (-2) * 2 = (-4). The number that adds up to -4 gives zero, +4, that is, in this gas it has an oxidation state of +4. A more complicated example: H2SO4 - hydrogen has an oxidation state of +1, oxygen has -2. In this compound there are 2 hydrogen molecules and 4 oxygen molecules, i.e. the charges will be +2 and -8, respectively. In order to get a total of zero, you need to add 6 pluses. This means that the oxidation state of sulfur is +6.
When it is difficult to determine where is plus and where is minus in a compound, an electronegativity table is needed (it is easy to find in a general chemistry textbook). Metals often have a positive oxidation state, while non-metals often have a negative oxidation state. But for example, PI3 - both elements are non-metals. The table indicates that the electronegativity of iodine is 2.6, and that of phosphorus is 2.2. When compared, it turns out that 2.6 is greater than 2.2, that is, electrons are drawn towards iodine (iodine has a negative oxidation state). By following the simple examples given, you can easily determine the oxidation state of any element in compounds.
Please note
There is no need to confuse metals and non-metals, then the oxidation state will be easier to find and not get confused.
An atom of a chemical element consists of a nucleus and an electron shell. The nucleus is the central part of the atom, in which almost all of its mass is concentrated. Unlike the electron shell, the nucleus has a positive charge.
You will need
- Atomic number of a chemical element, Moseley's law
Instructions
Thus, the charge of the nucleus is equal to the number of protons. In turn, the number of protons in the nucleus is equal to the atomic number. For example, the atomic number of hydrogen is 1, that is, the hydrogen nucleus consists of one proton and has a charge of +1. The atomic number of sodium is 11, the charge of its nucleus is +11.
During the alpha decay of a nucleus, its atomic number is reduced by two due to the emission of an alpha particle (atomic nucleus). Thus, the number of protons in a nucleus that has undergone alpha decay is also reduced by two.
Beta decay can occur in three various types. In beta minus decay, a neutron turns into a proton by emitting an electron and an antineutrino. Then the nuclear charge increases by one.
In the case of beta-plus decay, the proton turns into a neutron, positron and nitrino, and the nuclear charge decreases by one.
In the case of electron capture, the nuclear charge also decreases by one.
The nuclear charge can also be determined from the frequency of the spectral lines of the characteristic radiation of the atom. According to Moseley's law: sqrt(v/R) = (Z-S)/n, where v is the spectral frequency of the characteristic radiation, R is the Rydberg constant, S is the screening constant, n is the principal quantum number.
Thus, Z = n*sqrt(v/r)+s.
Video on the topic
Sources:
- how does the nuclear charge change?
When creating theoretical and practical works in mathematics, physics, chemistry, a student or schoolchild is faced with the need to insert special characters and complex formulas. With the Word application from the Microsoft office suite, you can type an electronic formula of any complexity.
Instructions
Go to the "Insert" tab. On the right, find π, and next to it is the inscription “Formula”. Click on the arrow. A window will appear in which you can select a built-in formula, such as a quadratic formula.
Click on the arrow and a variety of symbols will appear on the top panel that you may need when writing this particular formula. After changing it the way you need, you can save it. From now on, it will appear in the list of built-in formulas.
If you need to transfer the formula to, which you later need to place on the site, then right-click on the active field with it and select not the professional, but the linear method. In particular, the same quadratic equation in this case will take the form: x=(-b±√(b^2-4ac))/2a.
Another option for writing an electronic formula in Word is through the constructor. Hold down the Alt and = keys at the same time. You will immediately have a field for writing a formula, and a constructor will open in the top panel. Here you can select all the signs that may be needed to write an equation and solve any problem.
Some linear notation symbols may not be clear to a reader unfamiliar with computer symbology. In this case, it makes sense to save the most complex formulas or equations in graphical form. To do this, open the simplest graphic editor Paint: “Start” - “Programs” - “Paint”. Then zoom in on the formula document so that it fills the entire screen. This is necessary so that the saved image has the highest resolution. Press PrtScr on your keyboard, go to Paint and press Ctrl+V.
Trim off any excess. As a result, you will get a high-quality image with the required formula.
Video on the topic
Under normal conditions, an atom is electrically neutral. In this case, the nucleus of an atom, consisting of protons and neutrons, is positive, and electrons carry a negative charge. When there is an excess or deficiency of electrons, an atom turns into an ion.
Instructions
Each has its own nuclear charge. It is the charge that determines the element number in the periodic table. So, the nucleus of hydrogen is +1, helium is +2, lithium is +3, +4, etc. Thus, if an element is known, the charge of the nucleus of its atom can be determined from the periodic table.
Since the atom is electrically neutral under normal conditions, the number of electrons corresponds to the charge of the atom's nucleus. The negative is compensated by the positive charge of the nucleus. Electrostatic forces hold electron clouds close to the atom, which ensures its stability.
When exposed to certain conditions, electrons can be removed from an atom or additional ones can be added to it. When you remove an electron from an atom, the atom becomes a cation, a positively charged ion. With an excess number of electrons, an atom becomes an anion, a negatively charged ion.
Algorithm for composing the electronic formula of an element:
1. Determine the number of electrons in an atom using the Periodic Table of Chemical Elements D.I. Mendeleev.
2. Using the number of the period in which the element is located, determine the number of energy levels; the number of electrons in the last electronic level corresponds to the group number.
3. Divide the levels into sublevels and orbitals and fill them with electrons in accordance with the rules for filling orbitals:
It must be remembered that the first level contains a maximum of 2 electrons 1s 2, on the second - a maximum of 8 (two s and six r: 2s 2 2p 6), on the third - a maximum of 18 (two s, six p, and ten d: 3s 2 3p 6 3d 10).
- Principal quantum number n should be minimal.
- First to fill s- sublevel, then р-, d- b f- sublevels.
- Electrons fill the orbitals in order of increasing energy of the orbitals (Klechkovsky's rule).
- Within a sublevel, electrons first occupy free orbitals one by one, and only after that they form pairs (Hund’s rule).
- There cannot be more than two electrons in one orbital (Pauli principle).
Examples.
1. Let's create the electronic formula of nitrogen. Nitrogen is number 7 on the periodic table.
2. Let's create the electronic formula for argon. Argon is number 18 on the periodic table.
1s 2 2s 2 2p 6 3s 2 3p 6.
3. Let's create the electronic formula of chromium. Chromium is number 24 on the periodic table.
1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 5
Energy diagram of zinc.
4. Let's create the electronic formula of zinc. Zinc is number 30 on the periodic table.
1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10
Please note that part of the electronic formula, namely 1s 2 2s 2 2p 6 3s 2 3p 6, is the electronic formula of argon.
The electronic formula of zinc can be represented as:
Electronic configuration an atom is a numerical representation of its electron orbitals. Electron orbitals are regions of various shapes located around the atomic nucleus in which it is mathematically probable that an electron will be found. Electronic configuration helps quickly and easily tell the reader how many electron orbitals an atom has, as well as determine the number of electrons in each orbital. After reading this article, you will master the method of drawing up electronic configurations.
Steps
Distribution of electrons using the periodic system of D. I. Mendeleev
- For example, a sodium atom with charge -1 will have an extra electron in addition to its base atomic number 11. In other words, the atom will have a total of 12 electrons.
- If we are talking about a sodium atom with a charge of +1, one electron must be subtracted from the base atomic number 11. Thus, the atom will have 10 electrons.
-
Remember the basic list of orbitals. As the number of electrons in an atom increases, they fill the various sublevels of the atom's electron shell according to a specific sequence. Each sublevel of the electron shell, when filled, contains an even number of electrons. The following sublevels are available:
Understand electronic configuration notation. Electron configurations are written to clearly show the number of electrons in each orbital. Orbitals are written sequentially, with the number of atoms in each orbital written as a superscript to the right of the orbital name. The completed electronic configuration takes the form of a sequence of sublevel designations and superscripts.
- Here, for example, is the simplest electronic configuration: 1s 2 2s 2 2p 6 . This configuration shows that there are two electrons in the 1s sublevel, two electrons in the 2s sublevel, and six electrons in the 2p sublevel. 2 + 2 + 6 = 10 electrons in total. This is the electronic configuration of a neutral neon atom (neon's atomic number is 10).
-
Remember the order of the orbitals. Keep in mind that electron orbitals are numbered in order of increasing electron shell number, but arranged in increasing order of energy. For example, a filled 4s 2 orbital has lower energy (or less mobility) than a partially filled or filled 3d 10 orbital, so the 4s orbital is written first. Once you know the order of the orbitals, you can easily fill them according to the number of electrons in the atom. The order of filling the orbitals is as follows: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p.
- The electronic configuration of an atom in which all orbitals are filled will be as follows: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6 7s 2 5f 14 6d 10 7p 6
- Note that the above entry, when all orbitals are filled, is the electron configuration of element Uuo (ununoctium) 118, the highest numbered atom in the periodic table. Therefore, this electronic configuration contains all the currently known electronic sublevels of a neutrally charged atom.
-
Fill the orbitals according to the number of electrons in your atom. For example, if we want to write down the electron configuration of a neutral calcium atom, we must start by looking up its atomic number in the periodic table. Its atomic number is 20, so we will write the configuration of an atom with 20 electrons according to the above order.
- Fill the orbitals according to the order above until you reach the twentieth electron. The first 1s orbital will have two electrons, the 2s orbital will also have two, the 2p will have six, the 3s will have two, the 3p will have 6, and the 4s will have 2 (2 + 2 + 6 +2 +6 + 2 = 20 .) In other words, the electronic configuration of calcium has the form: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 .
- Note that the orbitals are arranged in order of increasing energy. For example, when you are ready to move to the 4th energy level, first write down the 4s orbital, and then 3d. After the fourth energy level, you move to the fifth, where the same order is repeated. This happens only after the third energy level.
-
Use the periodic table as a visual cue. You've probably already noticed that the shape of the periodic table corresponds to the order of the electron sublevels in the electron configurations. For example, the atoms in the second column from the left always end in "s 2", and the atoms on the right edge of the thin middle section always end in "d 10", etc. Use the periodic table as a visual guide to writing configurations - how the order in which you add to the orbitals corresponds to your position in the table. See below:
- Specifically, the leftmost two columns contain atoms whose electronic configurations end in s orbitals, the right block of the table contains atoms whose configurations end in p orbitals, and the bottom half contains atoms that end in f orbitals.
- For example, when you write down the electronic configuration of chlorine, think like this: "This atom is located in the third row (or "period") of the periodic table. It is also located in the fifth group of the p orbital block of the periodic table. Therefore, its electronic configuration will end with. ..3p 5
- Note that elements in the d and f orbital region of the table are characterized by energy levels that do not correspond to the period in which they are located. For example, the first row of a block of elements with d-orbitals corresponds to 3d orbitals, although it is located in the 4th period, and the first row of elements with f-orbitals corresponds to a 4f orbital, despite being in the 6th period.
-
Learn abbreviations for writing long electron configurations. The atoms on the right edge of the periodic table are called noble gases. These elements are chemically very stable. To shorten the process of writing long electron configurations, simply write the chemical symbol of the nearest noble gas with fewer electrons than your atom in square brackets, and then continue writing the electron configuration of subsequent orbital levels. See below:
- To understand this concept, it will be helpful to write an example configuration. Let's write the configuration of zinc (atomic number 30) using the abbreviation that includes the noble gas. The complete configuration of zinc looks like this: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10. However, we see that 1s 2 2s 2 2p 6 3s 2 3p 6 is the electron configuration of argon, a noble gas. Simply replace part of the electronic configuration for zinc with the chemical symbol for argon in square brackets (.)
- So, the electronic configuration of zinc, written in abbreviated form, has the form: 4s 2 3d 10 .
- Please note that if you are writing the electronic configuration of a noble gas, say argon, you cannot write it! One must use the abbreviation for the noble gas preceding this element; for argon it will be neon ().
Using the periodic table ADOMAH
-
Master the periodic table ADOMAH. This method of recording the electronic configuration does not require memorization, but requires a modified periodic table, since in the traditional periodic table, starting from the fourth period, the period number does not correspond to the electron shell. Find the periodic table ADOMAH - a special type of periodic table developed by scientist Valery Zimmerman. It is easy to find with a short internet search.
- In the ADOMAH periodic table, the horizontal rows represent groups of elements such as halogens, noble gases, alkali metals, alkaline earth metals, etc. Vertical columns correspond to electronic levels, and the so-called "cascades" (diagonal lines connecting blocks s,p,d and f) correspond to periods.
- Helium is moved towards hydrogen because both of these elements are characterized by a 1s orbital. The period blocks (s,p,d and f) are shown on the right side, and the level numbers are given at the bottom. Elements are represented in boxes numbered 1 to 120. These numbers are ordinary atomic numbers, which represent the total number of electrons in a neutral atom.
-
Find your atom in the ADOMAH table. To write the electronic configuration of an element, look up its symbol on the periodic table ADOMAH and cross out all elements with a higher atomic number. For example, if you need to write the electron configuration of erbium (68), cross out all elements from 69 to 120.
- Note the numbers 1 through 8 at the bottom of the table. These are numbers of electronic levels, or numbers of columns. Ignore columns that contain only crossed out items. For erbium, columns numbered 1,2,3,4,5 and 6 remain.
-
Count the orbital sublevels up to your element. Looking at the block symbols shown to the right of the table (s, p, d, and f) and the column numbers shown at the base, ignore the diagonal lines between the blocks and break the columns into column blocks, listing them in order from bottom to top. Again, ignore blocks that have all the elements crossed out. Write column blocks starting from the column number followed by the block symbol, thus: 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 6s (for erbium).
- Please note: The above electron configuration of Er is written in ascending order of electron sublevel number. It can also be written in order of filling the orbitals. To do this, follow the cascades from bottom to top, rather than columns, when you write column blocks: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 12 .
-
Count the electrons for each electron sublevel. Count the elements in each column block that have not been crossed out, attaching one electron from each element, and write their number next to the block symbol for each column block thus: 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 4f 12 5s 2 5p 6 6s 2 . In our example, this is the electronic configuration of erbium.
-
Be aware of incorrect electronic configurations. There are eighteen typical exceptions that relate to the electronic configurations of atoms in the lowest energy state, also called the ground energy state. They don't obey general rule only in the last two or three positions occupied by electrons. In this case, the actual electronic configuration assumes that the electrons are in a state with a lower energy compared to the standard configuration of the atom. Exception atoms include:
- Cr(..., 3d5, 4s1); Cu(..., 3d10, 4s1); Nb(..., 4d4, 5s1); Mo(..., 4d5, 5s1); Ru(..., 4d7, 5s1); Rh(..., 4d8, 5s1); Pd(..., 4d10, 5s0); Ag(..., 4d10, 5s1); La(..., 5d1, 6s2); Ce(..., 4f1, 5d1, 6s2); Gd(..., 4f7, 5d1, 6s2); Au(..., 5d10, 6s1); Ac(..., 6d1, 7s2); Th(..., 6d2, 7s2); Pa(..., 5f2, 6d1, 7s2); U(..., 5f3, 6d1, 7s2); Np(..., 5f4, 6d1, 7s2) and Cm(..., 5f7, 6d1, 7s2).
- To find the atomic number of an atom when it is written in electron configuration form, simply add up all the numbers that follow the letters (s, p, d, and f). This only works for neutral atoms, if you're dealing with an ion it won't work - you'll have to add or subtract the number of extra or lost electrons.
- The number following the letter is a superscript, do not make a mistake in the test.
- There is no "half-full" sublevel stability. This is a simplification. Any stability that is attributed to "half-filled" sublevels occurs because each orbital is occupied by one electron, so repulsion between electrons is minimized.
- Each atom tends to a stable state, and the most stable configurations have the s and p sublevels filled (s2 and p6). Noble gases have this configuration, so they rarely react and are located on the right in the periodic table. Therefore, if a configuration ends in 3p 4, then it needs two electrons to reach a stable state (to lose six, including the s-sublevel electrons, requires more energy, so losing four is easier). And if the configuration ends in 4d 3, then to achieve a stable state it needs to lose three electrons. In addition, half-filled sublevels (s1, p3, d5..) are more stable than, for example, p4 or p2; however, s2 and p6 will be even more stable.
- When you are dealing with an ion, this means that the number of protons is not equal to the number of electrons. The charge of the atom in this case will be depicted at the top right (usually) of the chemical symbol. Therefore, an antimony atom with charge +2 has the electronic configuration 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 1 . Note that 5p 3 has changed to 5p 1 . Be careful when the neutral atom configuration ends in sublevels other than s and p. When you take away electrons, you can only take them from the valence orbitals (s and p orbitals). Therefore, if the configuration ends with 4s 2 3d 7 and the atom receives a charge of +2, then the configuration will end with 4s 0 3d 7. Please note that 3d 7 Not changes, electrons from the s orbital are lost instead.
- There are conditions when an electron is forced to "move to a higher energy level." When a sublevel is one electron short of being half or full, take one electron from the nearest s or p sublevel and move it to the sublevel that needs the electron.
- There are two options for recording the electronic configuration. They can be written in ascending order of energy level numbers or in the order of filling electron orbitals, as was shown above for erbium.
- You can also write the electronic configuration of an element by writing only the valence configuration, which represents the last s and p sublevel. Thus, the valence configuration of antimony will be 5s 2 5p 3.
- Ions are not the same. It's much more difficult with them. Skip two levels and follow the same pattern depending on where you started and how large the number of electrons is.
Find the atomic number of your atom. Each atom has a certain number of electrons associated with it. Find your atom's symbol on the periodic table. The atomic number is a positive integer starting at 1 (for hydrogen) and increasing by one for each subsequent atom. Atomic number is the number of protons in an atom, and therefore it is also the number of electrons of an atom with zero charge.
Determine the charge of an atom. Neutral atoms will have the same number of electrons as shown on the periodic table. However, charged atoms will have more or less electrons, depending on the magnitude of their charge. If you are working with a charged atom, add or subtract electrons as follows: add one electron for each negative charge and subtract one for each positive charge.
