Atoms, elements and compounds

Question 1

There are over __ different elements, which are made up of atoms.

Answer 1

100

Question 2

___ are used to help explain elements, compounds and mixtures.

Answer 2

Particle diagrams

Question 3

Some elements exist as individual __, but some bond together to form __ of the same element.

Answer 3

atoms
molecules of atoms

Question 4

Why could the iron be separated easily from the sulfur before they were heated together, but not afterwards?

Answer 4

Iron is a magnetic element, so it can be separated from a mixture using a magnet. But after the iron and sulfur have been heated, they react to make the compound iron sulfide. You cannot easily separate an element from a compound.

Question 5

An element is a pure substance that cannot be broken down into any other ___.

Answer 5

substances

Question 6

An element is made from just one type of __

Answer 6

atom

Question 7

Some elements exist as individual ___, but some exist as.

Answer 7

atoms
molecules

Question 8

Most of the elements are ___.

Answer 8

metals

Question 9

How many chemical elements do you think there are?

Answer 9

there are actually 118 chemical elements

Question 10

The air we breathe is mostly made from __ and __

Answer 10

nitrogen
oxygen

Question 11

In the periodic table metals are found on the __

Answer 11

left

Question 12

In the periodic table non_metals are found on the __

Answer 12

right

Question 13

Describe properties ofr Hydrogen

Answer 13

It is an explosive gas which burns with a very clear ‘squeaky pop’ when a burning splint is inserted into a test tube containing it.

Question 14

Helium is also a gas, but is very different from hydrogen because it doesn’t take part in any ___

Answer 14

chemical reactions.

Question 15

Scientists Marie and Pierre Curie discovered two elements: __ and __ . For these discoveries, Marie Curie received a .

Answer 15

radium
polonium
Nobel prize

Question 16

___ can be used to show the atoms of elements. All of the atoms in a particle diagram must be the same __ and__ .

Answer 16

Particle diagrams
colour
size

Question 17

In a solid element the particles are ___ and arranged in a ___

Answer 17

close together
regular way

Question 18

In a liquid element the particles are ___ and arranged in a ___

Answer 18

close together
random way

Question 19

In a gaseous element the particles are ___ and arranged in a ___

Answer 19

apart
random way

Question 20

Some non-metal elements are made from atoms which are bonded into clusters called ____.

Answer 20

molecules

Question 21

A ___ is a pure substance that is made from more than one element. In a __ , elements are chemically bonded together, which makes it very difficult to separate them.

Answer 21

compound
compound

Question 22

When a compound is made, the atoms of the elements bond together in a fixed ___ . This means that each compound can be represented by a

Answer 22

ratio
chemical formula.

Question 23

the formula of water is __

Answer 23

H₂O

Question 24

the formula of carbon dioxide is __

Answer 24

CO₂.

Question 25

To break apart the elements in a compound, a ___ must take place.

Answer 25

chemical reaction

Question 26

What is electrolysis?

Answer 26

Splitting up a liquid or dissolved compound into its elements using electricity.

Question 27

What is thermal decomposition?

Answer 27

Breaking down a compound into its elements, or simpler compounds using a high temperature.

Question 28

When elements make a compound through a physical process such as ___ or ___ , it is impossible to separate them.

Answer 28

filtration boiling

Question 29

A particle diagram for a compound will show more than one type of \_\_

Answer 29

atom

Question 30

Water molecules are made up of __ elements -\_\_\_ and\_\_ .

Answer 30

two hydrogen oxygen

Question 31

Carbon dioxide molecules are made up of __ elements - __ and \_\_.

Answer 31

two carbon oxygen

Question 32

Compounds made from non-metal elements that are bonded together usually form \_\_.

Answer 32

molecules

Question 33

Compounds including both a __ element and a __ element bonded together do not form molecules.

Answer 33

metal non-metal

Question 34

Compounds including both a metal element and a non-metal element bonded together form a \_\_\_

Answer 34

lattice

Question 35

A ___ is formed when two or more elements or compounds are present without being chemically bonded together.

Answer 35

mixture

Question 36

Substances which have been mixed are not present in specific ___ or __ like they are in a compound

Answer 36

amounts ratios

Question 37

In a mixture, the two ingredients can be separated using ___ , without chemical reactions.

Answer 37

physical processes

Question 38

A mixture of sand and water can be separated using \_\_\_

Answer 38

filtration

Question 39

A solution of salt and water can be separated using __ or \_\_\_

Answer 39

crystallisation distillation

Question 40

A mixture of iron filings and sulfur powder can be separated using a ___ .

Answer 40

magnet

Question 41

Air is a mixture which is made mainly of ___ molecules and ___ molecules.

Answer 41

nitrogen oxygen

Question 42

Whereabouts on the periodic table are the non-metals found?

Answer 42

On the right.

Question 43

Which technique is most likely to be used to separate the elements which are bonded together in a compound?

Answer 43

Thermal decomposition. Thermal decomposition can be used to break down some compounds into elements. Simple techniques like filtration and evaporation will not work, but they can be used for separating mixtures.

Question 44

Letters from the alphabet are used to represent chemical ___ .

Answer 44

elements

Question 45

An element’s chemical symbol is a single ___ letter or a capital letter followed by a __ letter.

Answer 45

capital lower case

Question 46

The __ shows the chemical symbols for all the different elements.

Answer 46

periodic table

Question 47

The formula H₂O is used to represent water. What does the formula mean?

Answer 47

The formula H₂O shows that water is made from two atoms of hydrogen (H) bonded to one atom of oxygen (O).

Question 48

What is an element?

Answer 48

An element is a substance that cannot be broken down into any other substance. Every element is made up of its own type of atom.

Question 49

Elements are represented by letters from the alphabet. These letters are also known as ___ .

Answer 49

symbols

Question 50

The symbol H is for \_\_\_

Answer 50

hydrogen

Question 51

The symbol C is for \_\_\_

Answer 51

carbon

Question 52

The symbol He is for \_\_\_

Answer 52

helium

Question 53

The symbol Mg is for \_\_\_

Answer 53

magnesium

Question 54

The symbol Na is for \_\_\_

Answer 54

sodium

Question 55

A lot of the element names have come from Latin. The Latin name for sodium was '\_\_\_'.

Answer 55

natrium

Question 56

Which element has the symbol N?

Answer 56

Nitrogen.

Question 57

There are 118 chemical elements and they are listed on the periodic table. ___ chemical elements occur naturally on Earth and in the universe. elements are made using nuclear reactions.

Answer 57

94 24

Question 58

The formula of a compound shows how many __ of each element are bonded together.

Answer 58

atoms

Question 59

The formula is made up of ___ and.

Answer 59

symbols numbers

Question 60

Water is a compound of hydrogen and oxygen. The symbols H for hydrogen and O for oxygen are used to represent .

Answer 60

H₂O

Question 61

Oxygen gas is a molecule made of two oxygen (O) atoms represented as .

Answer 61

O₂

Question 62

Sulfuric acid is a combination of hydrogen (H), sulfur (S) and oxygen (O) represented as

Answer 62

H₂SO₄.

Question 63

For compounds made from metals and non-metals, the ratio is simplified down as much as possible. The formula for Natrium Choldire is __ instead of Na₈Cl₈.

Answer 63

NaCl

Question 64

Calcium chloride has the formula CaCl₂, so there are __ as many chlorine atoms present as calcium atoms.

Answer 64

twice

Question 65

Many non-metal elements are made from molecules, and these have a chemical formula which shows how many __ are bonded to each other in their molecules.

Answer 65

atoms

Question 66

Which elements does MgCl₂ contain? How many of each type of atom are present?

Answer 66

MgCl₂ is the formula for magnesium chloride, which is a compound containing magnesium (Mg) and chlorine (Cl). There are two atoms of chlorine for every one atom of magnesium.

Question 67

Carbon exists in different forms, including __ , ___ and __ .

Answer 67

graphite diamond graphene

Question 68

Carbon atoms are arranged in a regular pattern, meaning carbon is __ at room temperature.

Answer 68

solid

Question 69

Nitrogen makes up about __ of the Earth's atmosphere.

Answer 69

78% o

Question 70

Nitrogen isn't very reactive, but it can react with oxygen at high temperatures, such as in car engines. These reactions make __ .

Answer 70

nitrogen oxides

Question 71

The boiling point of nitrogen is __ , so liquid nitrogen is very cold indeed. This means liquid nitrogen is ideal for freezing food, such as vegetables, very quickly, allowing them to stay fresher for longer.

Answer 71

−196 °C