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78 terms

TBHSWK yr11 chemistry Sci 1.5

Terms and definitions for the Sci 1.5 Chemistry paper "Demonstrate an Understanding of Aspects of Acids and Bases
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Acid
A substance which gives H+ ions in solution.
Base
A chemical which gives hydroxide ions in a reaction.
Alkali
A base which will dissolve in water eg. NaOH
Alkaline solution
A solution with a ph above 7
pH
A number scale which indicates the degree of acidity or alkalinity
Neutralise
To make the pH of a solution equal 7
Hydrogen ions
A positively charged hydrogen atom
Hydroxide ions
Ions formed from bases in a reaction (OH- )
Neutral
Solution which is neither acidic nor alkaline (ph = 7).
Evaporate
To remove liquid from a solution by changing it into a gas.
Compound
A substance where different types of atoms are chemically bonded in fixed amounts.
Salt
A compound formed when a metal or base reacts with an acid.
Hydrogen test
A flame makes this gas explode with a squeaky pop.
Oxygen test
Glowing splint placed in this gas relights.
Carbon dioxide test
Clear limewater turns milky when this gas is bubbled through it.
Limewater
Chemical used to test for carbon dioxide gas.
Metals
Elements that are shiny, malleable, ductile and good conductors of heat and electricity
Carbonates
Compounds which release carbon dioxide with acid.
Bicarbonates
Another name for Hydrogen carbonates.
Calcium Hydroxide
The chemical name for limewater
Soluble
Able to be dissolved
Acid rain
Rain that has a ph less than 7
Antacid
Chemical that helps neutralise an acid (eg stomach acid)
Neutralisation
Reaction between an acid and a base
Strong acid
Acids which give all of their hydrogen ions in a reaction
Weak acid
Acids which give only a few of their hydrogen ions in a reaction
Strong base
A base which gives lots of hydroxide ions in a reaction
Weak base
A base which gives only a few hydroxide ions in a reaction
Dilute
A small amount of chemical dissolved in a given volume
Concentrated
A large amount of chemical dissolved in a given volume
Matter
Anything that has mass and occupies space
Element
Substance made up of one type of atom only
Mixture
Substance made from different elements or compounds that are not chemically joined
Compound
Substance made of two or more elements joined together chemically in fixed amounts
Atom
Very small particles which make up all matter
Nucleus
Central part of an atom made up of protons and neutrons.
Proton
Positively charged subatomic particle
Electron
Very small, negatively charged subatomic particles
Neutron
Uncharged subatomic particles
Neutral atom
An atom with equal numbers of protons and electrons
Atomic number
Number of protons in an atom
Mass number
Number of protons and neutrons in an atom
Electron shell
Space that electrons with equal energy occupy
Valence electrons
Electrons in the outer shell of an atom
Periodic table
Chart with elements arranged in periods and groups
Group
A column of the periodic table
Period
A row of the periodic table
Isotope
Atoms of the same element with a different mass number due to different numbers of neutrons
Ion
An atom or group of atoms that has lost or gained electrons
Cation
Positively charged ion (because it has lost electrons)
Anion
Negatively charged ion (because it has gained electrons)
Molecular formula
Shows the number and type of atoms in a formula
Bond
The attractive force which holds particles in a substance together
Ionic bond
Bond formed by attractions of positive cation to negative anion
Covalent bond
Bond in which atoms share electrons equally to get a full shell
Chemical reaction
What occurs when new chemical substances are formed
Reactants
The starting substances in a reaction
Products
The new substances formed in a reaction
Balanced equation
Writing a reaction using the formulae of chemicals
Molecule
A group of atoms covalently joined together
Ionic compound
Compound made up of positive and negative ions
Molecular compound
Compound made up of atoms joined covalently together
Reaction rate
How fast a chemical reaction occurs
Collision theory
Explains that a reaction will only occur if the reactants collide with enough energy to break existing bonds
Frequency of collisions
The number of collisions by reactants
Effectiveness of collisions
The right alignment and force of collisions between reactants
Concentration
Amount (in moles per Litre) of a substance
mol L-1
Moles per Litre - unit of concentration
Temperature
Average kinetic energy of substances
0C
Unit of temperature
Surface area
Area of the particles exposed for collisions
Catalyst
Substance which speeds up a reaction without being used up
Enzyme
A biological catalyst
Industrial catalyst
Catalysts which speed up industrial processes to make them more efficient and economical
Activation energy (EA)
The minimum amount of energy needed to start a reaction
Exothermic reaction
Chemical reaction which gives out energy
Endothermic reaction
Chemical reaction which takes in energy
Orientation of reactants
The way the reactants are in the right alignment or position before colliding