1(c) - Atomic Structure

Question 1

What is meant by the term atom?

Answer 1

An atom is the smallest part of an element.

Question 2

What is meant by the term molecule?

Answer 2

A molecule is made of a fixed number of atoms covalently bonded together.

Question 3

Describe the structure of an atom:

Answer 3

An atom consists of a central nucleus, composed of protons and neutrons. This is surrounded by electrons, orbiting in shells (energy levels). Atoms are neutral because the numbers of electrons and protons are equal.

Question 4

What is the mass of protons, electrons and neutrons?

Answer 4

protons: 1
neutrons: 1
electrons: 1/1836

Question 5

What is the atomic number?

Answer 5

The number of protons in an atom.

Question 6

What is the mass number?

Answer 6

The number of protons and neutrons in an atom.

Question 7

What is an isotope?

Answer 7

Atoms of the same element (same number of protons) but with a different number of neutrons.

Question 8

What is the relative atomic number (Ar)?

Answer 8

The weighted average mass of the isotopes of the element, relative to the mass of 1/12th of a C-12 atom.

Question 9

How do you calculate the relative atomic mass?

Answer 9

1. Multiply the mass of each isotope by its relative abundance
2. Add those together
3. Divide by the sum of the relative abundances (normally 100)