Year 10 Chem

What are the two ways matter is divided?

1. Pure Substances
2. Mixtures

What is a pure substance?

Substances with fixed physical and chemical properties alongside chemical reactivity because they are made of one type of chemical subunit.

What are mixtures?

Substances with variable physical and chemical properties because they are made of more than one type of chemical subunit.
They are physical combinations of two or more pure substances which can be physically separated.

What do pure substances include?

Elements and compounds

What are elements?

Substances that cannot be broken down into simpler substances

What are compounds?

Substances that have fixed physical and chemical properties but can be broken down into simpler substances because they consist of more than one type of atom.

What is a molecule?

A discrete arrangement of atoms joined by chemical bonds.

What is a lattice?

A network of atoms joined by chemical bonds.

How can atoms exist?

Individually, molecules, lattices.

What are the three subatomic particles atoms are made of?

Protons, neutrons and electrons

Where are protons and neutrons?

Formed as a cluster at the nucleus

Where are electrons?

Orbiting the nucleus in shells, forming an electron cloud.

What are protons?

Subatomic particles with a positive charge, have a mass of 1 atom unit. The protons determine the type of atom.

What is the atomic number of an atom?

The number of protons in an atom

What are neutrons?

Subatomic particles with no charge that have a mass of 1 atomic mass unit.

What is an isotope?

Atoms of the same element that have a different number of neutrons.

What is the mass number?

The total number of protons and neutrons in an atom.

What are electrons?

Subatomic particles with a negative charge, with a mass of 1/1840 of an atomic mass unity.

How to calculate the number of electrons.

equals the number of protons

What is the electron configuration?

The arrangement of electrons in shells around the nucleus.

How to calculate the maximum number of electrons in a shell

Sn^3 - This is extension work, likely not needed

Basic electron config.

2.8.8.2

What are periods?

The rows in the periodic table, representing the number of valence shells in an atom.
There are 7

What are the inner transition metals called?

lanthanides and actinides

What are groups?

The columns on the periodic table, representing the number of valence shells in an atom.

Properties of alkali metals

Group 1
Soft, Shiny.
Low melting and boiling points.
Highly reactive

Properties of alkaline earth metals

Group 2
Silver-white metals
Low melting and boiling points

Properties of Transition metals

Groups 3-12
Hard metals
High boiling points
Form coloured compounds

Properties of Halogens

Group 17/7
Non-metal
Produce toxic, coloured vapours
low melting and boiling points
Diatomic molecules

Properties of noble gases

Group 18/8
Non metals
Exist as individual atoms
Very low melting and boiling points
Full valence shells
Unreactive

How does the size of atoms change by period?

The size of atoms increase with every period

How does the size of atoms change by group?

The size of atoms decrease with every group

How does the group of an element determine properties?

Elements of the same group have similar properties.

How does the chemical properties of atoms change by periods?

For Metals, they become more reactive with more valence shells
For non-metals, they become less reactive with more valence shells

How does the reactivity of elements change across groups?

Elements are less reactive towards the centre of the periodic table.

How are atoms arranged in metals?

A lattice of positive metal ions surrounded by valence electrons that are free to move, forming a "sea" of delocalised electrons.

Metallic properties

Lustre
Electrically and thermally Conductive
Malleable and ductile
High melting point
Hardness
Strength

What is lustre?

Shininess due to the reflection of light

What is an alloy?

A solid solution formed through a mixture of a metal and another element

What are the properties of alloys?

Enhanced physical and chemical properties
Greater resistance to corrosion

What are the three types of chemical bonds?

Metallic
Ionic
Covalent

What are the 5 chemical structures?

Metallic
Ionic
Covalent molecular
Covalent network
Monatomic

What are metallic and ionic bonds?

Electrostatic forces of attraction between positively charged metal ions and negatively charged electrons.

Why does ionic and covalent bonding occur?

To achieve a full valence shell

What is a positively charged ion called?

cation

What is a negatively charged ion called?

anion

What is the difference between monatomic and polyatomic ions

Monatomic is formed from single atoms whereas polyatomic are formed from multiple

Where are ionic bonds found?

In compounds

What are ionic structures?

Orderly, crystalline lattices consisting of alternating positive and negative ions

What are properties of ionic compounds?

Hard, brittle solids with high melting points
Soluble in water
Conduct electricity IF liquid or aqueous

What are covalent bonds?

The sharing of electrons between two non-metal atoms in order to gain full valence shells

Where can covalent bonds occur?

Both elements and compounds

What are the two ways covalent structures can form?

Discrete molecules (covalent molecular)
Continuous networks of atoms (covalent network)

What are covalent molecular structures?

Discrete molecules held together by covalent bonds.

Properties of covalent molecular structures

Low melting and boiling points
Usually gases or liquids
Do not conduct electricity

Examples of covalent molecular bonding

Cl2
H20
NH3
CH4

What are covalent network structures?

Continuous networks of atoms joined by covalent bonds

Properties of covalent network structures

Hard solids
High melting points
Do not conduct electricity
Unreactive

Examples of covalent network structures

C
SiO2

What are monatomic structures?

Individual atoms with no chemical bonds

Where are monatomic structures found?

Noble gases

What are properties of noble gases

Very low boiling points
Gases
Unreactive

What are the prefixes for covalent bonding

mono
di
tri
tetra
penta
hexa
hepta
octa
nona
deca

What is the octet rule?

Atoms tend to gain, lose or share electrons in order to have a full set of valance electrons.

What is a non-polar covalent bond?

equal sharing of electrons

What is a polar covalent bond?

unequal sharing of electrons

What is a polyatomic ion?

A group of covalently bonded atoms with a charge

How do ions attract and repel

Similarly charged repel
Opposite charges attract

List of diatomic molecules

hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, iodine

How are chemical reactions categorised?

Based on the way atoms and molecules are rearranged during the reaction

What are the main types of chemical reactions

Combination/Synthesis
Decomposition
Displacement (Single/double)
Combustion

What is a combination reaction + example?

Reactions involving two or more reactants forming a single product
A + B \= AB
H + O -\> H2O

What is a decomposition reaction + example?

Reactions involving a single reactant breaking down to form multiple products
AB -\> A + B
MG3N2 -\> Mg + N

What is a single displacement/replacement reaction + example?

Reactions that involve an element and compound to form an element and compound
A + BC -\> AC + B
Na + H2O -\> NaOH + H2

What is a double displacement/replacement reaction + example?

Reactions where two compounds form two compounds
AB + CD -\> AD + CB
NaOH + HCl -\> NaCl + H2O

What are the two unique reactions that occur from double displacement?

Precipitation
Neutralisation

What is a precipitation reaction?

Reactions where two soluble compounds in an aqueous solution combine to form an insoluble compound (the precipitate) and another compound.

What is a neutralisation reaction?

An acid and base combining to form a salt or water.

What is an example of a precipitation reaction?

"Golden Rain"
lead nitrate (aq) + potassium iodide (aq) -\> lead iodide (s) + potassium nitrate (aq)
Pb(NO3)2 + 2KI -\> PbI2 + 2KNO3

What is a combustion reaction?

Reactions that involve the burning of hydrocarbons with oxygen

What is a complete combustion reaction?

Reactions where the supply of oxygen is not limited
Products carbon dioxide and water
CxHy + O2 -\> CO2 + H2O
CH4 + 2O2 -\> CO2 + 2H2O

What is an incomplete combustion reaction?

Reactions where the supply of oxygen is limited.
Products can be carbon monoxide and water or carbon and water
CH4 + O2 -\> CO + H2O

What is a redox reaction?

A reaction where reduction and oxidation occurs simultaneously

What is reduction?

The loss of oxygen or the gain of electrons

What is oxidation?

The gain of oxygen or the loss of electrons

What is the reducing and oxidising agent?

The reducing is the one being oxidised, etc

What is an aqueous solution?

Substances dissolved in water

What is the law of conservation of mass?

Matter cannot be created nor destroyed

How to balance

RAP method
Reactants Amounts Products

What is the Mole

Avogadro's constant, 6.02 x 10^23

Equation for moles

n \= m/M

What is the limiting reactant?

the substance that is totally consumed when the chemical reaction is complete
Determines the amount of product

What is collision theory?

Collision theory states that for a reaction to occur, reactant particles must collide with sufficient energy and correct orientation to break bonds.

What is chemical kinetics?

The study of chemical reaction rates

How is reaction rate measured

The change in the amount of reactants or products over time
Therefore it can be measured in two ways:
1. How quickly reactants are consumed
2. How quickly products are formed.

Reaction rate formula

(change in amount of reactant/product)/time

How do chemical reactions progress?

Initially, the reaction is at its maximum rate, then it slowly decreases as the reaction progresses until it eventually stops

What are the two types of reaction rate

Instantaneous rate
Average rate

How to calculate average rate

Slope between two points

What are 5 indications that a chemical change has occurred?

1. Change in colour
2. Formation of a gas
3. Physical state alterations such as a precipitate forming
4. Temperature Change
5. Odour change