Chapter 2 Atoms, Ions And Compounds

Question 1

The atom consists of a nucleus made up of two types of subatomic particle, what are these?

Answer 1

Protons and Neutrons

Question 2

What subatomic particle occupies a region outside the nucleus?

Answer 2

An Electron - Electrons are arranged around the nucleus in shells

Question 3

What are the relative charges and relative Mass of the three subatomic particles?

Answer 3

Proton - 1+ Charge, relative mass of 1
Electron - 1- Charge, relative mass is negligible (1/1836th the mass of a proton)
Neutron - 0 Charge, relative mass is 1

Question 4

Why is nearly all of an atoms mass in the nucleus?

Answer 4

It contains protons and neutrons which are heavier than electrons located on shells around the nucleus

Question 5

The overall charge of an atom is zero - an atom is neutral. Why is this?

Answer 5

The total positive charge from protons is cancelled by the total negative charge from electrons

Question 6

What determines the identity of an atom?

Answer 6

The number of protons - Every atom of the same element contains the same number of protons. Different elements contain atoms that have different numbers of protons

Question 7

What is the periodic table listed in order of?

Answer 7

The number of protons (Atomic number)

Question 8

What is the atomic number?

Answer 8

Number of protons (and electrons)

Question 9

What is the mass number?

Answer 9

The number of protons and neutrons

Question 10

What are Isotopes?

Answer 10

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

OCR Definition - Atoms of the same element with different numbers of neutrons and different masses.

Question 11

What letter is atomic number represented by?

Answer 11

Z

Question 12

What letter is Mass number represented by?

Answer 12

A

Question 13

How can I work out the number of neutrons?

Answer 13

Mass number - Atomic number

Question 14

Why do different isotopes of an element react in the same way?

Answer 14

They contain the same number of electrons. The chemistry of an atom is determined by the behaviour of its electrons. The number of neutrons has no effect on reactions of an element, however isotopes of the same element have different numbers of neutrons and different masses therefore there may be small differences in physical properties with higher-mass isotopes having a higher mp, bp density ect - but the chemical reactions are the same

Question 15

What are positive ions called?

Answer 15

Cations - They have an overall positive charge (have more protons than electrons)

Question 16

What are negative ions called?

Answer 16

Anions - They have an overall negative charge (more electrons than protons)

Question 17

What is the mass defect?

Answer 17

The small amount of mass lost to hold the nucleus together

Question 18

Give the definition of relative isotopic mass

Answer 18

The mass of an isotope relative to 1/12th of the mass of an atom of carbon-12. Commonly used is the mass number. Carbon-12 is the international standard for measuring all relative masses.

Question 19

Define relative atomic mass (Ar)

Answer 19

The weighted mean mass of an atom relative to 1/12th of the mass of an atom of Carbon-12. The weighted mean mass takes into account the percentage abundance of each isotope and the relative isotopic mass of each isotope.

Question 20

How can relative atomic mass be calculated?

Answer 20

Using a mass spectrometer

Question 21

What are reactive molecular mass and relative formula mass used for?

Answer 21

Molecular formulae - simple molecular compounds (eg ethene)
Relative formula - giant ionic compounds (potassium chloride)