Atomic Structure and Bonding

Question 1

What is an atom

Answer 1

an atom is made up of a positively charged nucleus
surrounded by negatively charged cloud of electrons which areheld to the nucleus by electrostatic attraction. The nucleus itself consists of electrically neutral neutrons and positively charged protons. The atomic number of an element is the number of electrons or protons in the atom.

Question 2

three position of interatomic bonds under mechanical strain

Answer 2

(a)Neutral, relaxed or strain-free
position.
(b) Material strained in tension,
atoms further apart, material
gets longer.
(c) Material strained in
compression, atoms closer
together, material gets shorter.

Question 3

How do ionic bonds form

Answer 3

Ionic bonds form when a cation (positively charged ion) transfers an electron to an anion (negatively charged ion).
Ionic compounds are generally crystalline in nature and highly soluble in water.
Because of the strong electrostatic binding force, they are rigid and they have high melting points and high boiling points.

Question 4

What is covalent bonding

Answer 4

Covalent bonding is a sharing of electrons between two atoms.
These bonds are formed by overlapping electron orbitals, resulting in the lowering of the electron energy. Covalent bonds are localized and directional in nature and therefore, form definite angles between the bonds.

Question 5

What is metallic bonding

Answer 5

Metallic bonding is similar to covalent bonding. Electrons are shared but they are not bound to individual or to pairs of atoms as in covalent bonds. Instead these valence electrons are free to move throughout the entire metal, making metals such good
conductors.

Question 6

what is the van der waals bond

Answer 6

Van der Waals bonds are weak secondary bonds which can be found between covalently bonded chains of polymers and are also formed when molecules undergo polarization (a separation of the
charges in the molecule).