- Atom and Molecule: difference
Atoms are the smallest part of an element that can take part in a chemical reaction; molecules are the smallest particle of either an element or compound that can exist independently and at the same time keep the properties of the original substance, e.g. the smallest unit of water is the water molecule, which i made up of two atoms of hydrogen and one of oxygen
- Avogadro's Number (Symbol: NA )
- Chemical bonds
Many chemicals have a characteristic colour and this can help with it's classification or analysis. A special analytical tool that uses colour to determine a chemical, or measure a rate of reaction is called a Spectrometer
- Chemical matter
Chemistry is the scientific study of substances.
Atoms of a given element which have the same number of protons and electrons and the same chemical properties, but have a different number of neutrons in their nuclei, and consequently different atomic masses. Isotopes may be either stable or radioactive.
- Organic compounds
All compounds that contain carbon. All other compounds are inorganic
- PH a measure of the acidity or alkalinity of a solution.
Polymers are long--chain molecules in which a group of atoms are prepeated. They can be natural e., cellulose, DNA, fats, proteins and starches - or they can be artificial eg., nylon, polystyrene, polthene, PVC and in fact all by products of plastics
This is a measure of how much the path of a ray of light is bent when moving from one medium it is passing through, to another. This is very important in chemistry, as an analytical tool, as some chemicals are Optically active
- States of matter
- Sub-atomic particles
Chemical properties of elements depend on the structure of their atoms which are made up of three sub-atomic particles. Protons, which are positively charged, neutrons (neutral-no charge) and electrons which are negatively charged. Protons and neutrons are situated in the nucleus of the atom and the elctrons orbit the nucleus. The number of protons in the nucleus of the element determines the atomic number used in the periodic table.
Occurs when chemical matter changes directly from the solid to a gas without first melting into a liquid. Iodine is an example.
Propery of atoms or groups, equal to the number of atoms of hydrogen that the atom or group will combine with or displace in forming compounds