Atomic structure and Bonding

Question 1

What is an atom? How is it different from an element?

Answer 1

An atom is the smallest particle of an element which can participate in a chemical reaction. It is also considered the basic unit of matter. On the other hand, an element is a pure substance which is made up of one kind of atoms and cannot be broken down into 2 or more substances by an means.

Question 2

What are protons and neutrons called? Together, what can be obtained from them?

Answer 2

• Nucleons
• Mass number: It is the total number of protons and neutrons which is approximately the atomic mass of the atom in a.m.u.

Question 3

How can you find the atomic number of an atom?

Answer 3

Number of protons/electrons.

Question 4

An atom is electrically neutral. Explain.

Answer 4

As an atom contains equal number of positively charged protons and negatively charged electrons it is electrically neutral.

Question 5

What is the orbits of an atom also called? Which orbit has the most?

Answer 5

• Shells or Energy levels
• The outermost shell of an atom has maximum energy as it increases with distance from the nucleus.

Question 6

What is electronic configuration?

Answer 6

The electronic configuration is the distribution of atoms in the shells of an atom.

Question 7

Calcium has 20 electrons. Still, the penultimate shell has only 8 electrons, putting 2 in the last shell. Why?

Answer 7

As per the rule about maximum number of electrons in the shell, the 3rd shell should contain 18 electrons, however the outermost shell can never have more than 8 electrons and the penultimate shell cannot have more than 18. Thus, Calcium has its last 2 electrons in a separate shell.

Question 8

What are isotopes? Why is it that their chemical properties do not vary from that of an atom but their physical properties do?

Answer 8

• Atoms of the same element having same atomic number but different mass numbers. Chemical properties depend on the number of electrons unlike physical properties which depend on the atomic mass of an atom. Since the number of electrons does not change in isotopes only physical properties vary.

Question 9

Why is the atomic mass of chlorine a fraction?

Answer 9

It is the ratio of the average of all the isotopes of an element to the mass of 1/12th of carbon. Thus, the mas of chlorine is the average of 3+1 chlorine atoms. (142/4 = 35.5)

Question 10

What are noble gases?

Answer 10

• Elements with stable electronic configuration which means that their valence shells are complete and do not share, gain or lose electrons.

Question 11

What is based on the loss and gain of electrons? How?

Answer 11

• Electronic theory of oxidation and reduction
• As oxidation is the process of loss of electrons and reduction is the process of gain electrons