GCSE Chemistry- All Y10 Content

How many electrons do group one atoms have in their outer shell?

1

Properties of group 1 metals

fairly dense, malleable, can float on water

How is a positive ion formed?

It is formed when a metal atom loses electrons

How is a negative ion formed?

It is formed when a non-metal ion gains electrons

Ion

An atom with a positive or negative charge

Cations

positively charged ions

Anions

negatively charged ions

Ionic bonding

When positive ions and negative ions are strongly attracted to each other by electrostatic attraction

How should you refer to separate particles in ionic bonds?

ions

How should you refer to the compound in ionic bonding?

compound

What is the overall charge on any ionic compound?

0

Properties of ionic compounds

high melting and boiling points, are electrical conductors when liquid or aqueous

Giant Lattice Structure

When millions of ions are packed together in a regular cubic arrangement, joined by ionic bonds. There are strong electrostatic forces of attraction in giant lattice structures.

Why can ionic compounds carry a charge when liquid or aqueous?

Because the ions are free to move and carry a charge

Evaporation

When particles from the surface of a liquid turn into a gas. It can happen at any temperature between the melting and boiling point of a liquid.

Boiling

When all the particles in a liquid gain sufficient energy to turn into a gas. Can only occur at the boiling point of a liquid

What are the forces like between particles in a solid?

Strong

What is the arrangement of particles in a solid like?

Particles are in a fixed and regular arrangement.

How much energy do particles in a solid have?

Little (vibrate about fixed positions)

What is the arrangement of particles like in a liquid?

Particles are close and can move past each other. They are in an irregular arrangement.

What is the arrangement of particles like in a liquid?

Particles are close and can move past each other. They are in an irregular arrangement.

What is the arrangement of particles like in a liquid?

Particles are close and can move past each other. They are in an irregular arrangement.

How much energy do particles in a solid have?

More energy than solids (move at low speeds)

What are the forces of attraction in a gas like?

Weak

How are particles arranged in a solid?

Randomly. The particles are not touching and move freely

How much energy do particles in a gas have?

Particles have more energy than solids and liquids.

Gas to liquid

Condensing

Liquid to Solid

Freezing

Solid to Liquid

Melting

Liquid to Gas

Boiling/Evaporation

Gas to Solid

Deposition

Solid to Gas

Sublimation

Covalent Bonding

When non-metal atoms share electron pairs to obtain full outer shells

How should you refer to separate particles in covalent bonds?

atoms

How should you refer to a compound in covalent bonding?

molecule

What is the boiling point of a simple covalent molecule like?

Low

What are the bonds like within covalent molecules?

strong

What are the bonds like within covalent molecules?

strong

What are the melting and boiling points like in giant covalent structures?

Very high

In diamond structures, how many covalent bonds does each carbon atom form?

4

What are the covalent bonds in diamond like?

Strong, and therefore require a lot of energy to break

Properties of Diamond

High melting and boiling points, hard, very strong

In Graphite, how many covalent bonds does each carbon atom form?

3

After the carbon atoms have formed three covalent bonds in graphite, what does this leave?

A delocalised electron.

What can delocalised electrons do?

They can move between the layers and carry a charge through the structure.

What are the hexagonal rings of atoms in graphite called?

Graphene

What are layers of graphene held together with and what is the significance of this?

They are held together by weak intermolecular forces, which allow the layers to slide past one another

What molecules is silicon dioxide made of?

silicon and oxygen

How many oxygen atoms does each silicon atom bond to?

2

Why does graphene conduct electricity?

Because it only forms three covalent bonds, there is one delocalised electron which can move between the layers and carry a charge between the structure

What happens to reactivity as you descend group 7?

decreases

Why does reactivity decrease as you descend group 7?

Because the outer shell gets progressively further from the nucleus.

What type of reactions are halogen displacement reactions?

REDOX

What are the halogens?

group 7, primarily bromine, iodine, fluorine and chlorine

What colour is fluorine?

Yellow

What colour is chlorine?

Green

What colour is bromine?

Orange

What colour is Iodine?

Brown

Metallic Bonding

The strong electrostatic attraction between positive metal ions and a “sea” of shared, delocalised electrons, forming a giant, regular lattice structure.

Why are metals good conductors of heat and electricity?

Because delocalised electrons carry electrical charges and thermal energy through the whole structure.

Why do metals have high melting and boiling points?

Due to the strong electrostatic attraction between the positive metal ions and delocalised electrons, which require a lot of force to overcome.

Why are metals malleable?

Because the particles are arranged in neat rows which can slide over one another.

Advantages of dot and cross diagrams

• Gives ratio of atoms in the molecule

• Shows the type of single bond formed

Advantages of displayed diagrams

• gives the ratio of atoms in the molecule

• shows the type of single bond formed

Advantages of 3D models

• shows a 3D arrangement of atoms in space

• Shows the relative size of atoms in the molecule

• shows the relative bond angles

Disadvantages of dot and cross diagrams

• only a 2D representation

• doesn’t show relative sizes of atoms

disadvantages of displayed diagram

• only a 2D representation

• doesn’t show relative sizes of atoms in the molecule

disadvantages of 3D model

• doesn’t show the atoms in the molecule

• doesn’t show the type of single bond formed

Fullerenes

Hollow carbon structures usually shaped like empty tubes or balls.

What are fullerenes mainly made up of?

hexagonal rings of carbon atoms

What can fullerenes be used for?

drug delivery, catalysts, lubricants

What was the first fullerene to be discovered?

Buckminster fullerene

Alloys

An alloy is a mixture of two or more elements, where at least one element is a metal

Why are alloys stronger and harder than most metals?

Because the different sizes of metal atoms disrupt the neat, layered structure, meaning the layers can no longer slide over one another

What are steels?

Alloys of iron

Nanoparticles

very small particles

Properties of nanoparticles

high length to diameter ratio, high tensile strength, high melting and boiling points, conductors electricity and thermal energy

How many atoms do nanoparticles contain?

a few hundred

How large are nanoparticles?

1-100 nanometres

What is the size of one atom?

0.1-0.5 nanometres

What is a nanoparticle’s surface area to volume ratio like?

high

μm to nm

x1000

mm to μm

x1000

Equation for area

Area = length x width

Equation for Surface Area

surface area = area x 6

Equation for volume

volume = length x width x height

Why are nanoparticles good catalysts?

High SA:V ratio allows more collisions to occur on the surface of a catalyst.

Why are nanoparticles good for use in cosmetics?

Small particles provide better sunscreen protection

Why are nanoparticles good for use in Nanomedicine?

fullerenes are easily absorbed by the body, so are ideal for drug delivery

Why are nanoparticles good for use as lubricants?

Fullerenes can be used in artificial joints or gears to keep them smooth.

Why are nanoparticles good in electrical circuits?

Nanotubes (graphite) can conduct electricity and so are used in computer chips

What can happen if nanoparticles build up in cells?

Lung inflammation, as nanoparticles used in medicine do not break down easily.

Mass Number

Number of protons + Number of neutrons

Atomic Number

Number of protons (or electrons)

Isotopes

Atoms of the same element that contain the same number of protons but different numbers of neutrons.

Relative Atomic Mass (Ar)

The average mass of an atom of an element, compared to 1/12th of the mass of an atom of carbon-12

Relative Formula Mass (Mr)

The sum of the relative masses of atoms in a compound.

Unit for Mr

g mol^-1

How is the percentage of an element in a compound calculated?

By dividing the mass of the element in question by the relative formula mass of the compound and then multiplying the value by one hundred

What is Avogadro’s Number?

6.02 ×10²³