Formulae and equations Flashcards
Key concepts in chemistry
aqueous
Definition
Dissolved in water to form a solution. Shown as (aq) in chemical equations.
atom
Definition
The smallest part of an element that can exist.
balanced chemical equation
Definition
A chemical equation written using the symbols and formulae of the reactants and products, so that the number of units of each element present is the same on both sides of the arrow.
charge
Definition
Electrical charge can be positive or negative. Like charges (+ and + or - and -) repel but unlike charges (+ and -) attract each other.
compound
Definition
A substance formed by the chemical union of two or more elements.
covalent bond
Definition
A bond between atoms formed when atoms share electrons to achieve a full outer shell of electrons.
covalent compound
Definition
Compounds, commonly formed between non-metal elements, by sharing electrons between atoms to form covalent bonds. All molecular compounds are covalent.
electron
Definition
Subatomic particle, with a negative charge and a negligible mass relative to protons and neutrons.
element
Definition
A substance made of one type of atom only.
formula
Definition
A combination of symbols that indicates the chemical composition of a substance.
insoluble
Definition
Unable to dissolve in a particular solvent. For example, sand is insoluble in water.
ion
Definition
Electrically charged particle, formed when an atom or molecule gains or loses electrons.
ionic bonding
Definition
Ionic bonding forms between two atoms when an electron is transferred from one atom to the other, forming a positive-negative ion pair.
ionic compound
Definition
An ionic compound occurs when a negative ion (an atom that has gained an electron) joins with a positive ion (an atom that has lost an electron).
ionic equation
Definition
A chemical equation that shows how positively charged ions join with negatively charged ions to make a compound.
metal
Definition
Shiny element that is a good conductor of electricity and heat, and which forms basic oxides.
molecule
Definition
A collection of two or more atoms held together by chemical bonds.
non-metal
Definition
Element that is a poor conductor of electricity and heat, and which forms acidic oxides.
particle
Definition
A general term for a small piece of matter. For example, protons, neutrons, electrons, atoms, ions or molecules.
precipitate
Definition
A suspension of particles in a liquid formed when a dissolved substance reacts to form an insoluble substance, eg in a precipitation reaction.
precipitation reaction
Definition
A reaction in which an insoluble solid is formed when certain solutions are mixed.
product
Definition
A substance formed in a chemical reaction.
reactant
Definition
A substance that reacts together with another substance to form products during a chemical reaction.
soluble
Definition
Able to dissolve in solvent. For example, sugar is soluble in water because it dissolves to form sugar solution.