Unit 1-Glossary Flashcards
acid
An aqueous solution of a substance which has a pH less than 7. There is an excess of hydrogen ions, H+ in the solution.
alkali
An aqueous solution of a substance with a pH greater than 7 . There is an excess of hydroxide ions, OH- , in the solution.
alkali metals
Aqueous (aq)
Indicates that the substance has been dissolved in water.
atom
The smallest particle that can be obtained by chemical means. An atom consists of a nucleus containing protons and neutrons, surrounded by electrons
atomic number
The number of protons in the nucleus of the atom.
base
A compound which neutralises an acid to form a salt and water. Bases can be soluble or insoluble. Metal oxides and metal hydroxides are bases. Soluble bases form alkaline solutions
covalent bond
Formed when non-metal atoms join together by sharing electrons to achieve a full outer shell of electrons (electron arrangement the same as the nearest noble gas, group 0).
covalent compounds
A compound of non-metal atoms held together by covalent bonds.
Covalent network
A large structure of covalently bonded atoms.
Diatomic molecules
Contain two atoms. They can be elements e.g. Hydrogen, Oxygen, Nitrogen, Fluorine, Chlorine, Bromine and Iodine (H2,O2,N2,F2,Cl2,Br2,I2) or compounds e.g. hydrogen chloride, HCl
electrolysis
The process of breaking down of an ionic compound into its elements by the use of an electric current.
electron
A very small negatively-charged particle found in the space surrounding the nucleus of an atom.
Electron arrangement
The arrangement of electrons in shells (or energy levels) around the nucleus of an atom.
element
A substance containing only one kind of atom. It cannot be broken down further by chemical means.
endothermic
In an endothermic reaction, energy is taken in from the surroundings. There is a decrease in temperature.