Atoms, Elements and Compounds

Question 1

What is an element?

Answer 1

An element is made up of only one type of atom. It cannot be broken down into anything simpler.

Question 2

What is a compound?

Answer 2

Two or more elements chemically bonded in a fixed ratio.
This makes them difficult to separate and therefore need to undergo change if this were to happen.

Question 3

What is a mixture?

Answer 3

Two or more elements OR compounds that are not bonded and in a variable ratio.

Question 4

What are molecules?

Answer 4

Molecules are made up of 2 or more atoms of the same or different elements chemically bonded together

Question 5

What is the difference between a molecule and a compound?

Answer 5

Molecules can be made up of two atoms of the same kind.
All molecules are not compounds but all compounds are molecules.

Question 6

Which change is harder to reverse - chemical or physical?

Answer 6

Chemical

Question 7

Sodium chloride is a compound made from sodium and chlorine. Sodium fizzes when added to water. Explain why sodium chloride does not fizz when added to water.

Answer 7

After being chemically bonded to make a compound, some characteristics may not remain anymore as it is a completely different substance.

Question 8

What is an electron?

Answer 8

An electron is a subatomic particle found in shells (energy levels) around the nucleus.

Question 9

What is the charge of an electron?

Answer 9

Negative

Question 10

What is the charge of a proton?

Answer 10

Positive

Question 11

What are the characteristics of an electron?

Answer 11

• They have almost 0 mass
• Can be lost or gained in a reaction
• Found in shells
• Negatively charged

Question 12

Choose the correct option for the following:

Metals are shiny/not shiny
Metals have a high/low melting point
Metals are malleable/not malleable
Metals are ductile/not ductile
Metals are good/bad electrical conductors
Metals are good/bad thermal conductors

Answer 12

Shiny
High
Malleable
Ductile (ability to be stretched into wire)
Good
Good

Question 13

Choose the correct option for the following:

Non-Metals are shiny/not shiny
Non-Metals have a high/low melting point
Non-Metals are malleable/not malleable
Non-Metals are ductile/not ductile
Non-Metals are good/bad electrical conductors
Non-Metals are good/bad thermal conductors

Answer 13

Not shiny
Low
Not malleable
Not ductile
Bad
Bad

Question 14

What is the relative mass and relative charge of:
-a proton
-a neutron
-an electron

Answer 14

Proton: 1 and +1
Neutron: 1 and 0
Electron: almost 0 and -1

Question 15

What does the atomic number represent on the periodic table?

Answer 15

Amount of protons
Amount of electrons

Question 16

What does the mass number represent on the periodic table?

Answer 16

The sum of protons and neutrons

Question 17

How do you work out the number of neutrons?

Answer 17

Mass number - Atomic number

Question 18

What determines what type of atom it is?

Answer 18

The amount of protons

Question 19

What is an isotope?

Answer 19

An atom that has the same number of protons but a different number of neutrons.
They have the same atomic number but different mass number.
E.g. Carbon: C-12 C-13 C-14

Question 20

Why are C-12 C-13 and C-14 all still considered atoms of carbon despite being different?

Answer 20

They all still have 6 protons

Question 21

How would you simply describe what the Relative Atomic Mass is?

Answer 21

The average mass of an atom.

Question 22

How do you work out the relative atomic mass?

Answer 22

Ar = (mass number x percentage) + (mass number x percentage) /100

Question 23

How many electrons can the first second and third shells (energy levels) hold?

Answer 23

2,8,8

Question 24

What do the rows of the periodic table tell you about the elements?

Answer 24

How many shells there are
E.g. Potassium, third row, has 3 shells

Question 25

What does the column number tell you about an element?

Answer 25

What group the element is in and how many electrons are in the outer shell.

Question 26

Why is group 0/8 noble gases unreactive?

Answer 26

They already have a full outer shell which is the desired outcome. Other elements need to gain or lose electrons to get a full outer shell so they need to have a reaction. As noble gases don’t need to have a reaction, they do not need to be reactive.