Year 9 Chemistry Revision

What are the 3 subatomic particles?

Protons, neutrons and electrons.

What is the charge of a proton?

Positive (+1).

What is the charge of a neutron?

Neutral (0).

What is the charge of an electron?

Negative (-1).

Where are protons found?

In the nucleus.

Where are neutrons found?

In the nucleus.

Where are electrons found?

In electron shells around the nucleus.

What is the atomic number?

The number of protons in an atom.

How many electrons does a neutral atom have?

The same number as protons.

What is the periodic table?

A table that organises elements by atomic number and chemical properties.

What is a group?

A vertical column on the periodic table.

What do elements in the same main group have in common?

The same number of valence electrons.

What are valence electrons?

Electrons in the outermost electron shell.

What is a period?

A horizontal row on the periodic table.

What are common properties of metals?

They are usually shiny, strong, malleable, ductile and good conductors of heat and electricity.

What does malleable mean?

Can be hammered or pressed into sheets.

What does ductile mean?

Can be pulled into wires.

What is a physical change?

A change where no new substance is produced.

Give an example of a physical change.

Melting ice, boiling water or cutting paper.

What is a chemical change?

A change where one or more new substances are produced.

Give an example of a chemical change.

Burning, rusting or an acid reacting with a metal.

How can you tell if a chemical change occurred?

Signs can include colour change, gas production, temperature change, light or formation of a new solid.

What is an isotope?

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

Why are isotopes the same element?

They have the same number of protons.

How do you calculate neutrons?

Mass number minus atomic number.

What is electron configuration?

The arrangement of electrons in an atom's electron shells.

How many electrons fit in the first shell?

2 electrons.

How many electrons fit in the second shell?

8 electrons.

What is the rule of 8s?

Atoms tend to gain, lose or share electrons to achieve a full outer shell of 8 electrons.

What happens when an atom loses electrons?

It becomes a positive ion called a cation.

What happens when an atom gains electrons?

It becomes a negative ion called an anion.

What is a cation?

A positively charged ion formed when an atom loses electrons.

What is an anion?

A negatively charged ion formed when an atom gains electrons.

How do you remember cations?

Cation = positive; it has lost electrons.

How do you remember anions?

Anion = a negative ion.

What is ionic bonding?

Bonding involving the transfer of electrons, usually between a metal and a non-metal.

What happens in ionic bonding?

Electrons are transferred, forming positive and negative ions that attract each other.

What is covalent bonding?

Bonding where atoms share electrons, usually between non-metals.

What is the difference between ionic and covalent bonding?

Ionic = electrons are transferred. Covalent = electrons are shared.

What is combustion?

A chemical reaction involving burning, usually involving oxygen and releasing energy.

What are the products of complete hydrocarbon combustion?

Carbon dioxide and water.

What is an exothermic reaction?

A reaction that releases energy to the surroundings.

What happens to the surroundings in an exothermic reaction?

They usually become warmer.

What is an endothermic reaction?

A reaction that absorbs energy from the surroundings.

What happens to the surroundings in an endothermic reaction?

They usually become cooler.

How do you remember exothermic?

EXO = energy EXITS.

How do you remember endothermic?

ENDO = energy ENTERS.

What is the law of conservation of mass?

Mass cannot be created or destroyed in a chemical reaction.

What happens to atoms during a chemical reaction?

They are rearranged to form new substances.

What are reactants?

The substances you start with in a chemical reaction.

What are products?

The substances produced by a chemical reaction.

Why do chemical equations need to be balanced?

Because the same number of each type of atom must be present on both sides.

What is a coefficient?

A number placed in front of a chemical formula.

What is a subscript?

A small number within a chemical formula showing the number of atoms.

What can you change when balancing equations?

Only the coefficients in front of formulas.

What must you NEVER change when balancing equations?

The subscripts in chemical formulas.

What is the electron configuration of sodium?

2,8,1.

What happens when sodium forms an ion?

It loses one electron and becomes Na+.

What is the electron configuration of chlorine?

2,8,7.

What happens when chlorine forms an ion?

It gains one electron and becomes Cl-.

What type of bond forms between sodium and chlorine?

Ionic bonding.

What type of bond forms between non-metals?

Covalent bonding.

What is the general equation for combustion of a hydrocarbon?

Hydrocarbon + oxygen → carbon dioxide + water.

What is the general equation for an exothermic reaction?

Reactants → products + energy.

What is the general idea of an endothermic reaction?

Reactants + energy → products.What are the 3 subatomic particles?

What is the charge of a proton?

Positive (+1).

What is the charge of a neutron?

Neutral (0).

What is the charge of an electron?

Negative (-1).

Where are protons found?

In the nucleus.

Where are neutrons found?

In the nucleus.

Where are electrons found?

In electron shells around the nucleus.

What is the atomic number?

The number of protons in an atom.

How many electrons does a neutral atom have?

The same number as protons.

What is the periodic table?

A table that organises elements by atomic number and chemical properties.

What is a group?

A vertical column on the periodic table.

What do elements in the same main group have in common?

The same number of valence electrons.

What are valence electrons?

Electrons in the outermost electron shell.

What is a period?

A horizontal row on the periodic table.

What are common properties of metals?

They are usually shiny, strong, malleable, ductile and good conductors of heat and electricity.

What does malleable mean?

Can be hammered or pressed into sheets.

What does ductile mean?

Can be pulled into wires.

What is a physical change?

A change where no new substance is produced.

Give an example of a physical change.

Melting ice, boiling water or cutting paper.

What is a chemical change?

A change where one or more new substances are produced.

Give an example of a chemical change.

Burning, rusting or an acid reacting with a metal.

How can you tell if a chemical change occurred?

Signs can include colour change, gas production, temperature change, light or formation of a new solid.

What is an isotope?

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

Why are isotopes the same element?

They have the same number of protons.

How do you calculate neutrons?

Mass number minus atomic number.

What is electron configuration?

The arrangement of electrons in an atom's electron shells.

How many electrons fit in the first shell?

2 electrons.

How many electrons fit in the second shell?

8 electrons.

What is the rule of 8s?

Atoms tend to gain, lose or share electrons to achieve a full outer shell of 8 electrons.

What happens when an atom loses electrons?

It becomes a positive ion called a cation.

What happens when an atom gains electrons?

It becomes a negative ion called an anion.

What is a cation?

A positively charged ion formed when an atom loses electrons.

What is an anion?

A negatively charged ion formed when an atom gains electrons.

How do you remember cations?

Cation = positive; it has lost electrons.

How do you remember anions?

Anion = a negative ion.

What is ionic bonding?

Bonding involving the transfer of electrons, usually between a metal and a non-metal.