Chemical Reactions

The smallest unit of an element that still has the properties of that element, is made up of a nucleus containing protons and neutrons and electron shells containing electrons
Atomic number
The number of protons in an atom
A substance made up of atoms of two or more elements that are chemically combined
A subatomic particle that orbits an atoms’ nucleus, has a negative electric charge, and has very little mass
A substance made up of only 1 kind of atom
A substance that conducts heat and electricity well, is malleable, ductile, shiny and rings when hit, found on the left hand side of the periodic table
A subatomic particle that has the same mass as a proton, but has no electric charge
A subatomic particle that has the same mass as a proton, but has no electric charge
The centre of an atom, containing protons and neutrons
Periodic table
A table that shows the elements arranged in order by their atomic number
A subatomic particle that has a positive charge
The starting materials in a chemical reaction
The elements or compounds produced by a chemical reaction
Chemical Word Equation
A way to describe a chemical reaction using chemical names and other symbols
Alkali Metals
The group 1 metals, all have one electron in their outer shell and are very reactive
Alkaline earth metals
The group 2 metals, all have 2 electrons in their outer shell and are quite reactive
Electron configuration
The pattern of electrons in the electron shells, eg: Ca 2,8,8,2
Chemical change
Occurs when there is a chemical reaction, new substances are formed. The change cannot be easily reversed. May get a permanent colour change, energy change, gas given off etc
Physical change
The change can be easily reversed, it is not permanent. Nothing new has been formed. May be a change in state or dissolving etc.
Valence electron
An electron that is found in the outermost shell of an atom and determines the atoms chemical properties (how reactive it is)
Inert Gases
Group 18 (VIII) of the periodic table. All these elements have full outer shells and are not reactive
Elements with 7 electrons in their outer valence shell, in Group 17 (VII) of the periodic table. Very reactive.
Hydrogen gas
Made by reacting Magnesium metal with hydrochloric acid. Tested with a lighted splint that gives a squeaky ‘pop’
Oxygen gas
Made by reacting manganese dioxide with hydrogen peroxide. Tested with a glowing splint which relights
Carbon dioxide
Made by reacting calcium carbonate with hydrochloric acid and bubbling the gas through limewater, which goes cloudy
Burning, uses oxygen and a fuel, producing carbon dioxide and water
Incomplete combustion
Limited supply of oxygen. Carbon monoxide and carbon (soot) form instead of carbon dioxide
Conservation of mass
Mass of the reactants = mass of the products
A molecule is made up of two or more atoms (of the same element) bonded together eg: H2, O2, Cl2, S2

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