Periodic Table Cheat Sheet
Periodic table is prepared for classify elements according to their similarities in chemical and physical properties. In this table, elements are ordered to increasing atomic number.In periodic table, you can see atomic number, name, symbol and mass number of elements. As you can see from the picture given above, horizontal rows are called period and vertical columns are called group.
Orbitals in Periodic Table
s block: This blocks contains elements having valence electrons in s orbital. IA and IIA are s block groups.
p block: This blocks contains elements having valence electrons in p orbitals. IIIA, IVA, VA, VIA, VIIA and VIII A are p block groups.
d block: This blocks contains elements having valence electrons in d orbitals. IIIB, IVB, VB, VIB, VIIB, VIIIB, IB and IIB are d block groups.
f block: This blocks contains elements having valence electrons in f orbitals. Two elements mentioned in d block (IIIB) and two rows drawn at the bottom of periodic table are belong to f block.
a) Finding Period of Elements:
Period of the element is equal to highest energy level of electrons or principal quantum number.
16S: 1s22s22p63s23p4 3 is the highest energy level of electrons or principal quantum number. Thus period of S is 3.
b) Finding Group of Elements:
Group of element is equal to number of valence electrons of element or number of electrons in the highest energy level of elements. Another way of finding group of element is looking at sub shells. If last sub shell of electron configuration is "s" or "p", then group becomes A.Elements in group B have electron configuration ns and (n-1)d, total number of electrons in these orbitals gives us group of element. Look at following examples.
1) Atomic Radius:
Atomic radius of elements decreases as we go from left to right in periodic table.On the contrary, in same group, as we go from top to bottom, atomic radius of elements increase.
2) Ionization Energy:
Energy required to remove an electron from atoms or ions is called ionization energy. Increasing in the attraction force applied by nucleus to electrons makes difficult to remove electrons from shells. Second ionization energy is larger than first ionization energy, second ionization energy is larger than third ionization energy.
Changes of Ionization Energy in Periodic Table;
I A<III A<II A<IV A<VI A<V A<VII A<VIII A
3) Electron Affinity:
If an electron is added to neutral atom in gas state, energy is given off. We call this energy "electron affinity". Electron affinity increases as we go from left to right in period. On the contrary, electron affinity decreases in a group from top to bottom.
In a chemical bond, electron attraction capability of atoms is called electronegativity. From left to right in period electronegativity increases and from top to bottom in a group electronegativity decreases.
5) Metal-Nonmetal Property:
Capability of giving electron is called metal property and capability of getting electron is called non metal property of elements. Moving in period from left to right, metal property increases and non metal property decreases. In a group of metals, from top to bottom metal property increases. In a groups of non metals, from top to bottom non metal property of atoms decreases.
a) I A Alkaline Metals:
Except from 1H, all elements in this group are metal. They are 1H, 3Li, 11Na, 19K, 37Rb, 55Cs, 87Fr.They;
- have tendency to lose one electron in outer shells and become +1 ion
- are very reactive and exist in compounds
- are good conductors of electricity and heat
- all compounds of them are soluble in water
b) II A Alkaline Earth Metals:
All elements in this group are metal. They are 4Be, 12Mg, 20Ca, 38Sr, 56Ba, 88Ra. They;
- have tendency to lose two electrons in outer shells and become +2 ion
- are good conductors of electricity and heat in solid and liquid phases
- are reactive and exist in compounds
c) VII A Halogens:
All elements in this group are nonmetals.They are 9F, 17Cl, 35Br, 53I, and 85At. They;
- have higher tendency to bond electron and becomes -1 ion
- have seven electrons on outer shells, thus they can have values changing between +7 and -1 in compounds
- if they are in metal-nonmetal compounds they have -1 value
- they exist in diatomic molecules like F2, Br2
d) VIII A Noble Gases:
They are; 2He, 10Ne, 18Ar, 36Kr, 54Xe, 86Rn.
- have eight electrons on outer shells
- electron configurations end with ns2np6
- Noble gases are most stable elements and do not form compounds with other elements and each other.
- In normal conditions they exist in gas phase
- Ionization energies of them are higher than other group elements in same period
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