Chapter 4: Atomic Structure

Question 1

Define ‘proton number’

Answer 1

The proton number is the number of protons present in an atom. It is also known as the atomic number.

Question 2

What is the nucleon number?

Answer 2

The nucleon number of mass number is the total number of nucleons in the nucleus of an atom.

Nucleon nuber = total number of neutrons and proton

Question 3

Define an ‘isotope’

Answer 3

Isotopes are different atoms of the same element that have the same number of protons and electrons but different number of neutrons (same protons number but different nucleon number)

Isotopes of the same element have similar chemical properties but different chemical properties.

For physical properties like boiling point or melting point, isotopes of the same element have similar chemical properties but different physical properties.

Question 4

Define ‘relative abundance’

Answer 4

The reletive abundance of an isotope is the proportion of atoms with a specific atomic mass in a naturally occuring sample of an element. It can be expressed as a fraction, ratio or percentage.

Question 4

Define ‘relative isotope mass’

Answer 4

The relative isotope mass is the mass of an atom of an isotope compared to the mass of 1/2 of the mass of one carbon-12 atom.

Question 5

Define ‘relative atomic mass’

Answer 5

The relative atomic mass of an element, Ar, is the average mass of an atom of that element compared to 12 of the mass of one carbon-12 atom.

E.g. Cl’s Ar of 35.5

Question 6

Define ‘the valence shell’ of an electron

Answer 6

The outermost shell or valence shell is the electron shell that is the furthest away from the nucleus of the atom occupied by electrons.

Question 7

How do you identify a positive ion?

Answer 7

Positive ions always have fewer electrons than protons

Question 8

How do you identify a negative ion?

Answer 8

Negative ions always have more electrons than protons