atoms and molecules etcccc

Question 1

chemical reaction

Answer 1

A process in which one or more substances are changed into others, by their atoms being rearranged. Also known as irreversible reactions.

Question 2

physical reaction

Answer 2

A process in which the physical properties are changed into others, but no new substances are made. Also known as reversible reactions.

Question 3

Reactant

Answer 3

A substance that reacts together with another substance to form products during a chemical reaction.

Question 4

Product

Answer 4

A substance formed in a chemical reaction.

Question 5

Conservation of mass

Answer 5

The total mass of the products in a chemical reaction will be the same as the total mass of the reactants.

Question 6

periodic table

Answer 6

A tabular representation of all the known elements listed according to their atomic number. Organised in groups and periods.

Question 7

Physical properties

Answer 7

e.g Whether or not it is a good conductor of electricity, appearance, melting point, strength, density as a solid, metal or non-metal.

Question 8

Chemical properties

Answer 8

Describe how a substance reacts or changes into other substances (like reactivity- the tendency of an element to undergo a chemical reaction.)

Question 9

Chemical reactivity

Answer 9

The tendency of an element to undergo a chemical reaction.

Question 10

Compound

Answer 10

Where two or more elements have chemically joined together.

Question 11

Groups

Answer 11

A vertical column in the periodic table containing elements with similar chemical properties

Question 12

Endothermic

Answer 12

Reactions that take in heat by extracting thermal energy from the surroundings leading to a temperature decrease.

Question 13

Exothermic

Answer 13

Reactions that give out heat leading to an increase in heat, eg combustion, neutralisation and oxidation.

Question 14

Periodic table

Answer 14

Tabular representation of all known elements organised in atomic number, and in groups and periods.

Question 15

molecule

Answer 15

A group of two or more atoms chemically bonded together.

Question 16

Physical properties

Answer 16

Characteristic of a substance that can be observed or measured without changing the identity of the substance. Physical properties include color, density, hardness, and melting and boiling points.

Question 17

Thermal decomposition

Answer 17

Some compounds break down when heated, forming two or more products from one reactant.

Question 18

Limewater

Answer 18

Colourless but turns cloudy when there is carbon dioxide bubbled through it with a tube.

Question 19

Atom

Answer 19

The smallest part of an element

Question 20

Mixture

Answer 20

Two or more substances that are not joined together. These substances can be elements, compounds or both.

Question 21

Element

Answer 21

A substance made of only one type of atom

Question 22

Periods (rows)

Answer 22

A horizontal row in the periodic table that all share the same number of electron shells.

Question 23

Atomic Number

Answer 23

The number of protons in the nucleus of an atom. Also called the proton number.

Question 24

Combustion

Answer 24

Burning fuel in oxygen. (Complete combustion-all the oxygen is used up, incomplete combustion-if there is not enough oxygen in the air.) Combustion is another name for burning.

Question 25

Thermal decomposition

Answer 25

When a substance is broken down into 2 or more substances by heat

Question 26

Reactivity series

Answer 26

A list of metals in order of reactivity.

Question 27

Displacement

Answer 27

A more reactive metal will displace the less reactive metal from its compound.

Question 28

Catalyst

Answer 28

A substance that increases the rate of a reaction but is not itself used up.

Question 29

Polymer

Answer 29

Long chain molecules made up of many monomers.

Question 30

Fuel

Answer 30

Contain hydrocarbons - compounds containing hydrogen and carbon atoms only.

Question 31

Activation energy

Answer 31

The minimum amount of energy that colliding particles must have for them to react.

Question 32

Oxidation

Answer 32

Where a substance gains oxygen. Metals and non-metals can take part in oxidation reactions, eg copper oxide.

Question 33

How do you test for Hydrogen (H2)

Answer 33

Makes lit splint burn with squeaky pop. If H2 is present in a test tube, a lit splint held near it's mouth ignites with a squeaky pop.

Question 34

How do you test for Oxygen (O2)

Answer 34

Relights a glowing splint. If Oxygen is present in a test tube, a glowing splint relights when it is held inside.

Question 35

How do you test for Chlorine (Cl2)

Answer 35

Bleaches damp blue litmus paper white. Hold the litmus paper in a test tube filled with chlorine

Question 36

The combustion of magnesium with Oxygen.

Answer 36

.Heat crucible with lid on .Lift lid gently with tongs to allow O2 in .Heat for 5 more minutes, letting a little O2 in until it doesn't glow brightly .Remove the lid and heat 5 more minutes .Allow to cool, re-weigh crucible. It's still very hot. The mass before burning was normally higher than the mass after burning

Question 37

What is the air made up of

Answer 37

Air mostly consists of nitrogen (78.09%), oxygen (20.95%), and argon (0.93%). It also has trace amounts of other gases like carbon dioxide (0.04%), water vapor, Neon, helium, methane, krypton, hydrogen, nitrous oxide, xenon, ozone, iodine, carbon monoxide, and ammonia, all present in very small quantities.

Question 38

Air pressure in a can

Answer 38

If there is unequal air pressure inside a can, the can will be crushed.

Question 39

How to measure the volume of Oxygen in a container of air.

Answer 39

light candle, place it in a jar, and water level will rise as the candle uses up the oxygen. MATERIALS tealight Clear glass jar/container tray/dish Water ruler or measuring tape (optional)