2. From the Compounds of Matter to the Periodic Table

1. Measurements and Dimensions 포스팅 👉https://surfer1225blog.com/measurements-and-dimensions/

2.1 The Atom and its Structure

Particle	Electric Charge	Mass
Electron	-1.6 * (10)^(-19)C	9.11 * (10)^(-31) Kg
Proton	+1.6 * (10)^(-19)C	1.67 * (10)^(-27) Kg
Neuron	0	1.67 * (10)^(-27) Kg

I. Atomic number and Mass number

Atomic number Z = number of protons

Mass Number A = sum of protons + neurons

II. Ion, Anion, Cation and Isotopes

Ion : if number of protons does not match the number of electrons

1. anion : gain of electron
2. cation : loss of electron

if number of protons(Z) is same but different mass number(A) -> isotopes

III. Radioactive Decay

1. Alpha decay : a new atom is obtained
   • Zf = Zi – 2eAf = Ai -4
2. Beta decay : results in a new atom
   • β+ : Zf = Zi + 1
   • β- : Zf = Zi -1

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2. 2 The Periodic Table and its Properties

• 7 horizontal periods = valence shell
• 18 vertical groups = valance electrons

Group 1	Alkali metals(알칼리 금속)
Group 2	Alkaline earth metals(알칼리성 토금속)
Group 3 – 12	Transition Metals
Group 13	–
Group 14	–
Group 15	–
Group 16	–
Group 17	Halogens(할로겐)
Group 18	Noble Gases(비활성 기체)

	Definition	Trend
Atomic Radius(원자반지름)	Half the distance btw centers of nuclei of two atoms of the same element	increases down the group decreases across the period
Ionization Energy(IE, 이온화 에너지)	Minimum energy required to remove an electron from an isolated atom in gaseous form	increases across the period decreases down the group
Electron Affinity(EA, 전자 친화도)	Energy released when an electron is added to a neutral isolated atom in gaseous form	increases across the period decreases down the group
Electronegativity(전기음성도)	Tendency of atoms to attract bonding electrons from another atom when forming a chemical bond	increases across the period decreases down the group

참고 : https://www.thoughtco.com/periodicity-on-the-periodic-table-608795

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2.3 Oxidation Number(산화수)

: hypothetical charge that an element would have in compound if all valence electrons were assigned to the most electronegative atom

Element	Oxidation Number
Alkali metals	+1
Alkaline earth metals	+2
Group III	+3
Group IV	+2, +4
Group V	+3, +5
Group VI	+4, +6
Group VII	±1, +3, +5, +7
Group VIII	0

** Oxygen : -2(almost always), 1(peroxides like H2O2), +1(Fluorine peroxide O2F2)

** Hydrogen : +1(metal hybrid), =1(covalent hydrid, acid)