C1 Atoms (Part 2)

Question 1

Describe the plum-pudding

model

Answer 1

A sphere of positive charge with negative electrons embedded in it.

Question 2

Describe the Bohr/nuclear model and how it came about

Answer 2

The nuclear model suggests that electrons orbit the nucleus at specific
distances (shells) – it came about from the alpha scattering experiments

Question 3

Later experiments led to the discovery of smaller, positive particles in the nucleus; what are these particles called?

Answer 3

Protons

Question 4

What did the work of James Chadwick provide evidence for?

Answer 4

The existence of neutrons in the nucleus

Question 5

Describe the structure of an atom

Answer 5

The atom has a small central nucleus (made up of protons and neutrons)
around which there are electrons

Question 6

State the relative masses and relative charges of the proton, neutron and electron

Answer 6

Relative Mass / Charge
Proton –> 1, +1
Neutron –> 1, 0
Neutron –> very small (often taken as zero), -1

Question 7

Explain why atoms are electrically neutral.

Answer 7

They have the same number of electrons and protons

Question 8

What is the radius of an atom?

Answer 8

0.1 nm

Question 9

What is the radius of a nucleus and what is it compared to that of the atom?

Answer 9

1 x 10-14 m and 1/10000

Question 10

What is the atomic number?

Answer 10

The number of protons in the nucleus

Question 11

Atoms of the same element have
the same number of which particle
in the nucleus?

Answer 11

Protons

Question 12

Where is the majority of

mass of an atom?

Answer 12

The nucleus

Question 13

What is the mass number?

Answer 13

The total number of protons and neutrons

Question 14

How does one calculate the number of neutrons using mass number and atomic number?

Answer 14

Mass number minus atomic number

Question 15

What is an isotope?

Do isotopes of a certain element have the same chemical properties?

Answer 15

Atoms of the same element (same proton number) that have a different number of neutrons.
They have the same chemical properties as they have the same electronic structure

Question 16

What is the relative atomic mass?

Answer 16

It is an average mass taking into account the different masses and abundances (amounts) of all the isotopes that make up the element.

Ar = sum of (isotope abundance x isotope mass number) / sum of abundances of all isotopes

Question 17

Give the electronic configurations of
He (2), Be (4), F (9), Na (11), and Ca
(20) to demonstrate how shells are
occupied by electrons.

Answer 17

2
 2,2
 2,7
 2,8,1
 2,8,8,2

Question 18

What are ions?

When are they formed?

Answer 18

Ions are charged particles. They are formed when atoms lose electrons
(positive ions) or gain (negative ions) electrons.
E.g. sodium positive ion, Na+
, has an electronic configuration of 2,8 (same as Ne). An atom of sodium has lost one electron.

Question 19

What are the properties of METALS?

Answer 19

Metals:

• High Boiling Point
• Conduct Heat and Electricity
• Shiny
• Malleable
• Dense
• Basic Oxides

Question 20

What are the properties of NON-METALS?

Answer 20

Non Metals:

• Low boiling point
• Don’t conduct heat or electricity (except graphite)
• Dull
• Brittle
• Low density
• Acidic

Question 21

What is formed when a metal reacts with a non-metal?

Answer 21

An ionic compound (made of positive and negative ions).

Question 22

What is formed when a non-metal reacts with a non-metal?

Answer 22

A molecular compound containing covalently bonded atoms.
Atoms share electrons, as opposed to transferring electrons between
each other (cf. ionic compounds).