Chemistry Prior Knowledge
Acids and Bases
Chemical reactions
Scale from 0-14
7 is neutral (most water)
7-14 is basic
Acids commonly have a sour taste and can be corrosive
Atoms
0-7 is acidic
An atom is the smallest amount of an element that is possible to get
Some bases that are solid can be dissolved in water, these are called an alkali
Atoms are comprised of Neutrons, Protons and electrons
Most bases have a slippery feeling and bitter taste
When universal indicator is poured into a base it will turn blue/ violet to show that it is basic.
When universal indicator is poured into an acid it will turn orange/ red to show that it is acidic.
these are each made up of smaller sub-atomic particles, electrons, protons and nuetrons
Acids release H+
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A compound is a group of atoms bonded together by chemical bonds.
Bases release OH-
Cations have a positive charge
A chemical element is a substance that contains only one type of atom, which is the smallest particle of an element.
Anions have a negative charge
Atoms have a nuetral charge
Neutrons and protons can be found in the nucleus of an atom.
An atomic number is based on the amount of protons in the atom's nucleus
In a neutral atom there is always an equal number of protons and nuetrons
the mass number is the total number of protons and neutrons. This is how isotopes are expressed
Isotopes are atoms that have the same number of protons and electrons. They have a different number of neutrons but changing the number of neutrons in an atom doesn’t change the element. Atoms of elements with different numbers of neutrons are called isotopes of that element.
A chemical reaction is a process that re arranges the ionic or molecular structure of substance
Combination reactions
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Solute: thing being dissolved
Solvent: Liquid that the solute is being dissolved in
Solution: The liquid mixture
Soluble: Dissolved in water
Insoluble: Precipitate do not dissolve in water
Precipitate reactions occurs when cations and anions in an aqueos solution combine to form and insoluble ionic solution called a precipitate.
decomposition reaction
displacement reaction
CHEMICAL CHANGE
A gas is given off
Their is a colour change
There is a different smell
Heat given out or absorbed
The change cannot be easily reversed
PHYSICAL CHANGE
The substance changes state (liquid to gas, solid to liquid etc)
No new substances are formed
The mass of the object is the same at the end of the change
The change can easily be reversed
changes in state of matter e'g: melting,sublimation freezing