CHEMISTRY [1 Mark Question Answer]

The periodic table is a tabular array of the chemical elements organized by atomic number, from the element with the lowest atomic number, hydrogen, to the element with the highest atomic number, oganesson. The atomic number of an element is the number of protons in the nucleus of an atom of that element.

Atomicity refers to the number of atoms present in a single molecule of an element, substance or compound. It can also be considered as the nature of molecules.

The molecule is defined as the smallest unit of matter, which has an independent existence and can retain the complete physical and chemical properties of the matter. Even when two or more atoms of the same kind combine they can form a molecule.

An atom is the basic building block of chemistry. It is the smallest unit into which matter can be divided without the release of electrically charged particles. It also is the smallest unit of matter that has the characteristic properties of a chemical element.

Hydrogen Sulphide

Zinc Sulphide

Zinc Chloride

Mercuric Oxide.

Copper Carbonate

Ammonium Hydroxide

Sodium Phosphate

Iron Sulphide

Calcium Nitrate

Ammonium Sulphate

Symbol Zn OH
Charge +2 -1
Formula = ​Zn(OH)₂

Symbol Ca HSO₄
Charge +2 -1
Formula = ​Ca(HSO₄)₂

Symbol Cu O
Charge +2 -2
Formula = ​Cu₂O₂ = CuO

Symbol NH₄ PO_{4
Charge +1 -3
Formula = ​(NH4)3PO4}

Symbol Pb NO_{3
Charge +2 -1
Formula = Pb(NO3)2}

Symbol NH₄Cl
Charge +1 -1
Formula = ​NH₄Cl

Symbol KSO_{4
Charge +1 -2
Formula = K2SO4}

Symbol Al N
Charge +3 -3
Formula = AIN

Symbol Fe SO₄
Charge +2 -2
Formula = FeSO₄

Symbol Na HCO_{3
Charge +1 -1
Formula = NaHCO3}

-1 = Chlorine, Bromine, Iodine.
-2 = Oxide, Sulphide, Sulphate.
-3 = Nitrogen, Nitride Phosphate.F1

The combining capacity of an atom is known as its valency. By gaining, sharing, and losing the electrons the atoms complete their outermost shell and make an octet. non-metals generally have electronegative valency.

- 1 = Hydrogen, Sodium, Potassium.
- 2 = Calcium, Magnesium, Zinc
- 3 = Aluminum, Chromium, Ferric

Metals have one to three electrons in their outermost shell, and they donate these electrons to other elements to attain a stable noble gas configuration. So, metals donate their electrons and form electropositive ions. Hence, metals generally have electropositive valency.

The combining capacity of an atom is known as its valency. The number of bonds that an atom can form as part of a compound is expressed by the valency of the element.

The number of protons (positively charged) and electrons (negatively charged) are equal in an atom. Therefore the opposite charges are balanced and thus there is no net charge on the atom. Moreover, neutrons present in the atom have no charge. Hence an atom is electrically neutral.