CHEMISTRY [2 Mark Question Answer]

Potassium chloride is an electrovalent compound and conducts electricity in the molten or aqueous state because the electrostatic forces of attraction weaken in the fused state or in aqueous solution.
Polar covalent compounds like hydrogen chloride ionise in their solutions and can act as an electrolyte. So, both can conduct electricity in their aqueous solutions.

Element A with 1 electron in its first shell is hydrogen, and element B with 7 electrons in its third shell is chlorine.
So, a single covalent bond is formed between hydrogen and chlorine by sharing one pair of electrons.

A single covalent bond is formed by sharing one pair of electrons between atoms, each atom contributes one electron.
A double bond is formed by the sharing of two pairs of electrons between two atoms.
A triple bond is formed by the sharing of three pairs of electrons between two atoms.

The charged particles which attract one another to form electrovalent compounds are called ions. Those having positive charge are called cations a those having negative charge are called anions.

Carbon-12 and carbon-14 are isotopes of carbon. They have the same atomic number (6) and hence the same electronic configuration. Chemical properties are determined by the electronic configuration of an atom. So, carbon-12 and carbon-14 show similar chemical properties.

Mass of an atom is contributed by mass of protons and mass of neutrons present inside the nucleus of an atom. Atoms of the same element contain the same number of protons but may differ in their number of neutrons. Therefore, an element has atoms with different mass numbers.

Atoms combine because they have incomplete valence shells and tend to attain a stable electronic configuration. So, to attain a stable electronic configuration, atoms of elements gain or share their electrons with other atoms.

Mass of an atom is contributed by mass of protons and mass of neutrons present inside the nucleus of an atom. Electrons present outside the nucleus are of negligible mass. Therefore, the mass of an atom is concentrated inside the nucleus of an atom.

Hydrogen chloride

Methane

Nitrogen

Orbital Diagram:
Magnesium chloride

Electrovalent compounds are usually formed between metals and non-metals.
Atoms of metallic elements that have 1, 2 or 3 valence electrons can lose an electron(s) to atoms of non-metallic elements that have 5, 6 or 7 valence electrons and thereby form an electrovalent bond.

Besides chaos, everything in this world wants stability. The same is the case with atoms. For atoms, stability means having the electron arrangement of inert gas, i.e. octet in the outermost shell. Helium has two electrons (duplet), while all other inert gases, i.e. neon, argon, krypton, xenon, and radon have eight electrons (octet) in the outermost shell.

Metals have a tendency to lose their valence electrons (1, 2 or 3). So, they combine with non-metals which have 7, 6 or 5 electrons in their valence shell to form an electrovalent bond.

Transfer of electron(s) is involved in the formation of an electrovalent bond. The electropositive atom undergoes oxidation, while the electronegative atom undergoes reduction. This is known as a redox reaction.

Fluoride ion is a negatively charged ion with 9 protons and 10 electrons.
Neon atom is electrically neutral with 10 protons and 10 electrons.

Elements tend to combine with one another to attain the stable electronic configuration of the nearest inert gas.
Hydrogen
A hydrogen atom has one electron in the valence shell which shares with another hydrogen atom having one electron to complete its duplet state, i.e. two electrons in the valence shell and resulting in the formation of hydrogen.

Actual atomic mass is greater than the mass number because the mass number is a whole number approximation of atomic mass unit. In fact, neutrons are slightly heavier than protons, and an atom has over 200 sub-atomic particles.

Argon does not react as it has the outermost orbit complete, i.e. 8 electrons in the outermost shell.

Nucleons: Particles which constitute the nucleus are called nucleons.
Protons and neutrons are the nucleons.
Atomic mass of phosphorus = 31
Atomic number = 15

Number of electrons in the M shell = 2
So, the number of electrons in the K and L shells will be = 2, 8
Hence, atomic number = 2 + 8 + 2 = 12
Number of protons = 12

Mass number = 24
Atomic number = 12
No. of electrons = 24 - 12 = 12
Electronic configuration = 2, 8, 2

p = proton
n = neutron
e = electron
Superscript number : These superscript number show their mass number
Subscript number : These numbers show their atomic number

(i) If the foil of a heavy metal like platinum (having a very heavy nucleus) is used, then the observations in the aa-particle scattering experiment would be the same as that in the gold foil experiment
(ii) If, however, the foil of a right metal like lithium (having a very light nucleus) is used, then the fast moving heavy aa-particles may even push the light nucleus aside and may not be deflected back.