Chem fc 🧪(combined)

Question 1

Define atom

Answer 1

The smallest part of an element that Dan exist

Question 2

Define compound

Answer 2

2 or more elements chemically combined

Question 3

Define mixture

Answer 3

2 or more elements not chemically combined

Question 4

Name 5 methods of separating mixtures

Answer 4

Filtration, crystallisation, simple distillation, fractional distillation, chromatography

Question 5

Describe the plum pudding model of the atom

Answer 5

Theatre is a ball of positive charge with negative electrons embedded in it

Question 6

Describe the method that led to the new model of the atom

Answer 6

The alpha particle scattering experiment. Most particles went straight through = empty space. Some deflected a little = positive centre. Some deflected back= large mass at cente

Question 7

Compare the plum pudding model to the nuclear model of the atom

Answer 7

Both have positive charge( pp in a ball, nuclear in nucleus as protons). Both have electrons( pp randomly spread, nuclear in shells). Nuclear has a nucleus and neutrons

Question 8

Why are atoms in the same group similar

Answer 8

They have the same number of electrons in their outer shell

Question 9

Who is responsible for the modern periodic tablw

Answer 9

Dimitri mendeleev

Question 10

What was mendeleev’s key innovation in making this table

Answer 10

He left gaps for undiscovered elements and changed the order in some places based on weights

Question 11

What charged ion do metal atoms form

Answer 11

All positive ions

Question 12

Describe group zero elements

Answer 12

Known as the noble gases are unreactive and have a full out of show

Question 13

Describe the Trend shown by group one elements

Answer 13

Reactivity increases down the group

Question 14

Describe the trends shown by group 7 elements

Answer 14

Reactivity decreases as you go down the group

Question 15

How does group number relate to the charge of an ion for elements in each group?

Answer 15

Group one equals +1, group two equals +2, group three equals +3, group 6 equals 2- group seven equals 1-

Question 16

Name the forces that hold ionic compounds together

Answer 16

Strong electrostatic forces

Question 17

Name 3 giant covalent structures and two very large covalent structures

Answer 17

Giant = diamond, graphite, silicon dioxide
Very large = carbon nanotubes , buckminsterfullerene

Question 18

Describe the bonding in metals

Answer 18

Positive metal ions, in neat rows, surrounded by a sea of delocalised electrons, held together by strong electrostatic forces

Question 19

Name the changes of state as you increase temperature

Answer 19

Melting, boiling

Question 20

Name the changes of state as you decrease temperature

Answer 20

Condensation, freezing

Question 21

What are the limitations of the particle model?

Answer 21

All particles are represented as solid spheres. All particles are shown the same size. There are no forces shown. It is two dimensional.

Question 22

How are the 4 states of matter represented in chemical equations?

Answer 22

Solid: (s) Liquid:(l) Gas: (g) Aqueous: (aq)

Question 23

In 3 sentences, explain the melting point of ionic compounds

Answer 23

Strong electrostatic forces between oppositely charged ions. Forces act in all directions in the lattice. A lot of energy needed to overcome so it has a high melting point.

Question 24

In what state do ionic substances conduct electricity, why?

Answer 24

Molton and aqueous, as the ions are free to move and carry charge

Question 25

Do covalent molecules conduct electricity? Why?

Answer 25

No, there are no charged particles

Question 26

In three sentences, explain the boiling point of simple covalent compounds

Answer 26

Made up of small molecules. Have weakened intermolecular forces. Little energy needed to overcome so have a low boiling point.

Question 27

Why are polymers solid at room temperature?

Answer 27

Intermolecular forces between polymer molecules are relatively strong. A lot of energy is needed to overcome these forces

Question 28

In 3 sentences, explain the melting point of diamond and graphite

Answer 28

Giant covalent structure. Has strong covalent bonds. A lot of energy needed to break these bonds so they have a very high melting point.

Question 29

Give 3 examples of giant covalent structures

Answer 29

Diamond graphite silicon dioxide

Question 30

Explain why metal Alloys are harder than pure metals

Answer 30

Pure metals have layers which can slide so they are soft. Alloys have different sized atoms which distort the layers so they cannot slide and so they are harder.

Question 31

Why are metals good conductors?

Answer 31

A sea of delocalised electrons in the Metal carry charge through the metal

Question 32

Why can graphite conduct electricity

Answer 32

Delocalised electrons carry charge through the structure

Question 33

State the law of conservation of mass

Answer 33

No atoms are lost of made during a chemical reaction so the mass of products equals the mass of reactants

Question 34

How would you calculate relative formula mass

Answer 34

Sum of the relative atomic masses of the atoms in the numbers shown in the formula

Question 35

What is a MOLE

Answer 35

The mess of 1 mole is the relative formula mass in grams. It is made up of 6x1023 particles

Question 36

What is meant by limiting reactant

Answer 36

The reactant that is completely used up in a chemical reaction

Question 37

Define reduction and oxidation

Answer 37

Oxidation is gain of oxygen and loss of electrons while reduction is loss of oxygen and gain of electrons

Question 38

Write an equation to describe the reaction of potassium with water

Answer 38

Potassium + water —> salt + hydrogen

Question 39

Why is gold found in its pure form but iron is not

Answer 39

Iron is more reactive than gold so reacts with oxygen in the air to form iron oxide. Gold is unreactive.

Question 40

Which element is used to extract a metal from its oxide

Answer 40

Carbon

Question 41

Which ions make acids and alkalis

Answer 41

Acid- H+ ions Alkalis - OH- ions

Question 42

Name 3 acids used in the science lab

Answer 42

Hydrochloric acid, sulphuric acid and nitric acid

Question 43

Name the types of salts produced by each acid

Answer 43

Hydrochloric- chloride salts sulphuric- sulphate salts nitric- nitrate salts

Question 44

Describe how a solid salt can be prefixed from a solution of that salt

Answer 44

Crystallisation- heat the solution to evaporate half the water, leave to cool and crystallise, scrape crystals from the surface and pat dry

Question 45

Describe how you can determine the pH of a solution

Answer 45

Universal indicator, pH probe

Question 45

Stir and ion equation for neutralisation

Answer 45

H+ + OH- —> H20

Question 46

Give the reason why some acids are strong and some are weak

Answer 46

Strong acids completely ionise. Weak acids only partially ionise.

Question 47

How are pH and acid strength related

Answer 47

As pH decreases by one unit, the concentration of hydrogen ions increases by a factor of 10

Question 48

Name the electrodes in electrolysis

Answer 48

Cathode and anode

Question 49

Why so solid ionic substances not conduct electricity

Answer 49

The ions are fixed in position and not free to move

Question 50

What is mixed with aluminium oxide in the industrial production of aluminium?

Answer 50

Cryolite

Question 51

What is the reason for mixing cryolite in with aluminium oxide

Answer 51

Reduces the melting point therefore saving energy

Question 52

Why might hydrogen be produced at the cathode

Answer 52

Water is also present so solution will contain H+ and OH- ions. Hydrogen will be released if it’s the least reactive of the metal and H+ ion

Question 53

Define exothermic

Answer 53

A reaction that transfers energy to the surroundings

Question 54

Define endothermic

Answer 54

Reaction that takes in energy from the surroundings

Question 55

Define activation energy

Answer 55

The minimum energy that particles must have to react