chemistry paper 1

its chem innit

What is the charge of a proton?

+1

What is the charge of a neutron?

0

What is the charge of an electron?

-1

What is the relative mass of a proton?

1

What is the relative mass of a neutron?

1

What is the relative mass of an electron?

Very small

How many types of atoms do elements contain?

Only one type

What are compounds?

Substances containing two or more different elements that are chemically bonded together

What are mixtures?

Substances containing two or more different elements that are not chemically bonded together

What pattern is formed from carrying out paper chromatography?

Chromatogram

Which method of separation is useful to separate an insoluble solid from a liquid?

Filtration

Which method of separation is useful to separate a soluble solid from a liquid?

Evaporation or Crystillisation

Which method of distillation separates liquids with similar boiling points?

Fractional distillation

Who discovered that the plum pudding model was wrong?

Ernest Rutherford

Who devised an experiment that proved the existence of the neutron?

Niels Bohr

Why did Mendeleev leave gaps in his Table of Elements?

To ensure that elements with similar properties stayed in the same groups. The gaps indicated the existence of undiscovered elements and allowed Mendeleev to predict what their properties might be

How are the group number and the number of electrons in the outer shell of an element related?

The group number tells you how many electrons are in the outer shell of an element. E.g. sodium is in Group 1 therefore it has 1 electron on its outer shell

What kind of ions do metals form?

Positive

Where are the non-metals on the periodic table?

On the right hand side

Give three properties which are specific to transition metals

1. They can form more than one ion e.g cobalt form Co2+

2. They are often coloured, therefore compounds which contain them are colourful e.g. potassium chromate is yellow

3. They often make good catalysts e.g. nickel based catalysts are used in the hydrogenation of alkenes

State three trends as you go down Group 1

1. Increased reactivity - the outer electron is more easily lost as the attraction between the nucleus and the electron decreases because the electron is further away from the nucleus

2. Lower melting and boiling points

3. Higher relative atomic mass

What are the products of the reaction of a Group 1 metal and water

Hydrogen gas and a metal hydroxide

E.g. sodium + water --> sodium hydroxide + hydrogen

What's the difference between the hardness of Group 1 and transition metals?

Transition metals are harder, denser and stronger than Group 1 metals

What's the difference between the reactivity of Group 1 and transition metals?

Group 1 metals are much more reactive than transition metals

What's the difference between the melting points of Group 1 and transition metals?

Transition metals have higher melting points than Group 1 metals

What trends occur as you go down Group 7?

1. They become less reactive - it's harder to gain an extra electron because the outer shell's further from the nucleus

2. They have higher melting and boiling points

3. They have higher relative atomic masses

What is the charge of the ions that halogens form when they react with metals?

They form negative ions

What is the trend in boiling point as you go down Group 0?

The boiling points increase

What subatomic particles does the nucleus contain?

Protons and neutrons

What is relative atomic mass?

The mass number which refers to the element as a whole

How are positive ions formed?

A metal atom loses electrons

How are negative ions formed?

A non-metal gains electrons

What is air a mixture of?

Gases, mainly nitrogen, oxygen, carbon dioxide and argon

What is crude oil a mixture of?

Different length hydrocarbon molecules

How can you separate substances in a mixture?

Chromatography

What is simple distillation used for?

Separating out a liquid from a solution

E.g. separating pure water from seawater

How were elements arranged in the early 1800s?

By their physical and chemical properties and their relative atomic mass

How are columns arranged?

Elements with similar properties

What are the three similar basic properties of metals?

1. They're strong but are malleable

2. They're great at conducting heat and electricity

3. They have high boiling and melting points

What is the product of the reaction of a Group 1 metal with chlorine?

A metal chloride salt

E.g. sodium + chlorine --> sodium chloride

What is the product of the reaction of a Group 1 metal with oxygen?

A metal oxide, depending on the Group 1 metal

-Lithium + oxygen --> lithium oxide

-Sodium + oxygen --> sodium oxide + sodium peroxide

-Potassium + oxygen --> potassium peroxide + potassium superoxide

What are halogens?

Non-metals in Group 7 with coloured vapours

What colour is fluorine?

A very reactive, poisonous yellow gas

What colour is chlorine?

A fairly reactive, poisonous dense green gas

What colour is bromine?

A dense, poisonous red-brown volatile liquid

What colour is iodine?

A dark grey crystalline solid or a purple vapour

What do halogens exist as?

Molecules - pairs of atoms

What do halogens form?

1. Molecular compounds - halogens share electrons via covalent bonding with other non-metals too achieves a full outer shell

2. Ionic compounds with metals - they form 1- ions called halides

What do noble gases exist as?

Monatomic gases - single atoms not bonded to each other

What are the noble gases at room temperature?

Colourless gases

Are the noble gases flammable?

No - they're non-flammable

Why does the boiling point of noble gases increase as you move down the group?

There's an increase in the number of electrons in each atom leading to greater intermolecular forces between them which to be overcome

Paper Chromatography - Method

1. Draw a pencil line near the bottom of a sheet of filter paper

2. Add a spot of ink to the line & place the sheet in a beaker of solvent e.g. water - the solvent used depends on what's being tested - some compounds dissolve well in water, but sometimes other solvents e.g. ethanol are needed

3. Ensure the ink isn't touching the solvent - you don't want it to dissolve

4. Place a lid on top of the container to stop the solvent evaporating

5. The solvent seeps up the paper, carrying the ink with it

6. Each different dye in the ink will move up the paper at a different rate so that the dyes will separate out - each dye will form a spot in a different place, 1 spot per dye in the ink

7. If any of the dyes in the ink are insoluble in the solvent used, they'll stay on the baseline

8. When the solvent has nearly reached the top of the paper, take the paper out of the beaker & leave it to dry

Simple Distillation - Method

1. The solution is heated. The part of the solution that has the lowest boiling point evaporates first

2. The vapour is then cooled, condensed & is collected

3. The rest of the solution is left behind in the flask

What is the problem with simple distillation?

You can only use it to separate things with very different boiling points - if the temperature goes higher than the boiling point of the substance with the highest boiling point, they will mix again

Fractional Distillation - Method

1. Put your mixture in a flask & stick a fractionating column on top. Then you heat it

2. The different liquids will all have different boiling points - they'll evaporate at different temperatures

3. The liquid with the lowest boiling point evaporates first. When the temperature on the thermometer matches the boiling point of this liquid, it will reach the top of the column

4. Liquids with higher boiling points might also start to evaporate, but the column is cooler towards the top, therefore they will only get part of the way up before condensing & running back down towards the flask

5. When the first liquid has been collected, you raise the temperature until the next one reaches the top

Radius of an atom

0.1 nanometers

Radius of a nucleus

1/10,000 of the radius of an atom

What type of ion do elements from Group 1 form?

Positive ions

What type of ion do elements from Group 7 form?

Negative ions

Describe how an ionic bond forms

When a metal and a non-metal react together, the metal loses its one electron on its outer shell to form a positively charged ion. This one electron is gained by the non-metal to complete its outer shell, forming a negative ion.

Describe the structure of a crystal of sodium chloride

It's a giant ionic lattice. The positive sodium and negative chlorine ions form a closely packed regular arrangement and there are very strong electrostatic forces of attraction between the oppositely charged ions.

List the main properties of ionic compounds

1. High melting and boiling points - many strong bonds between the ions

2. They can't conduct electricity when they're solid - the ions are held in a fixed arrangement therefore they can't pass on the electrical current.

3. They can conduct electricity when they're liquids because the ions are free to move therefore they can pass on the electrical current.

4. They dissolve easily in water - they are free to move in the solution and can carry electrical current.

Describe how covalent bonds form

When two non-metals bond together, they share electrons to make covalent bonds. The positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces - this makes covalent bonds very strong.

Explain why simple molecular compounds typically have low melting and boiling points

The intermolecular forces between the atoms are very weak, therefore it takes only a small amount of energy to break them apart.

Describe the structure of a polymer

Polymers are long chains of repeating units joined together to make a long molecule. Between the atoms are strong covalent bonds.

Give three examples of giant covalent substances

-Diamond

-Graphite