Answer is: As reactants form products, the potential energy decreases.
There are two types of reaction:
1) Endothermic reaction (chemical reaction that absorbs more energy than it releases).
2) Exothermic reaction (chemical reaction that releases more energy than it absorbs).
For example, balanced chemical reaction:
C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O ΔrH= -1370 kJ/mol.
This reaction is exothermic reaction (heat is released), so products have less potential energy and energy is transerred to surroundings.
Considering the definition of exothermic reaction, as reactants form products, the potential energy decreases (first option).
Energy is the ability to do work or to produce heat.
Chemical reactions involve a rearrangement of atoms between substances with the breaking or formation of chemical bonds. In general, this formation or breaking of chemical bonds is accompanied by changes in the energy of the system.
In exothermic reactions, energy is released when they occur (usually this energy is released in form of heat), so the reaction system temperature increases.
In a chemical reaction, the reactants are the compounds that are transformed and give rise to the products. Reactants and products have stored potential energy. In an exothermic reaction, the reactants have more potential energy compared to the products, so the excess energy is released as heat, thus complying with the law of conservation of energy, which says that energy is not lost. gain or loss, so the energy of the reactants must be equal to that of the products.
In summary, considering the definition of exothermic reaction, as reactants form products, the potential energy decreases (first option).
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b. uranium
c. sunlight
d. natural gas
alkaline earth metal.
halogen.
inner transition metal.
Atoms of different element can not have same atomic number because only same type of atoms combine to form element. Atoms belonging to different element can have different atomic number. Therefore, chlorine belongs to halogen family.
Element generally consist of atoms or we can atoms combine to form element. Atoms of an element is always same, means all the properties of all atoms of one type of element is same. Two or more than two atoms with different physical or chemical properties can not combine together to form an element.
Chlorine is a Halogen. These are all elements in Group 17 (right next to the Nobel Gases). Atomic number of chlorine is 17. Chlorine needs only one electron to completes its octet. Chlorine exist as gas.
Therefore, chlorine belongs to halogen family.
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(2) Br2(l) at 266 K (4) Br2(g) at 332 K
Answer is: (3) 2–8–17–6.
1) This is ground state of sodum atom.
Electron configuration of sodium atom: ₁₁Na 1s² 2s² 2p⁶ 3s¹.
Atomic number of sodium is 11, it means that it has 11 protons and 11 electrons, so atom of sodium is neutral.
2) This is ground state of sulfur atom.
Sulfur electron configuration: ₁₆S 1s²2s²2p⁶3s²3p⁴.
Sulfur has six valence electrons (3s²3p⁴), in 3s orbital, two electrons are paired, in 3p orbital, two electrons are paired and two are unpaired.
4) This is ground state of arsenic atom.
Electron configuration of arsenic atom:
₃₃As 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p³.
Electron configuration represents an excited state : (3) 2–8–17–6
In an atom there are levels of energy in the shell and sub shell
This energy level is expressed in the form of electron configurations.
Writing electron configurations starts from the lowest to the highest sub-shell energy level. There are 4 sub-shells in the shell of an atom, namely s, p, d and f. The maximum number of electrons for each sub shell is
Charging electrons in the sub shell uses the following sequence:
1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹⁰, 4p⁶, 5s², 4d¹⁰, 5p⁶, 6s², etc.
Determination of electron configurations based on principles:
According to Niels Bohr, electrons surround the nucleus of an atom on a path called the electron shell. Each shell has an energy level. The further from the core, the higher the energy level
Maximum electrons of shells :
The maximum number of electrons in each shell can be formulated = 2n² (n = shell number)
Electrons can move the shell up or down by releasing energy or absorbing energy
Excited electrons show higher electron transfer to the shell by absorbing energy
So it can be concluded that there are 2 conditions :
Ground state is the state of electrons filling skins with the lowest energy levels.
Excited state is the state of electrons which occupy a higher energy level
The state of excited electrons can be seen from the presence of electrons which do not fill the skin completely but fill the skin afterwards
From the electron configuration , option 3 shows the excitation of one electron in the M shell towards the N shell, which should have a configuration in the ground state:
2–8–18–5
element X
electrons and atomic orbitals
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Keywords: electron configurations, the shell of atoms, excited state