Classifying Materials

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Allotropes

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These are structurally-different forms of an element. They differ in the way the atoms bond with each other and arrange themselves into a structure. Because of their different structures, They have different physical and chemical properties

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Atom

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All elements are made of these. It consists of a nucleus containing protons and neutrons, surrounded by electrons.

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Compound

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This is a substance formed by the chemical union (involving bond formation) of two or more elements.

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Conduct

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To allow electricity, heat or other energy forms to pass through.

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Covalent Bond

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A bond between atoms formed when atoms share electrons to achieve a full outer shell of electrons.

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Double Bond

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A covalent bond resulting from the sharing of four electrons (two pairs) between two atoms.

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Ductile

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If a material is this it is capable of being drawn into thin sheets or wires without breaking.

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Electron

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This is a very small negatively-charged particle found in an atom in the space surrounding the nucleus.

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Electrostatic Force

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An electrostatic force is generated by differences in electric charge (ie positive and negative) between two particles. It can also refer to electricity at rest.

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Formula

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This is a combination of symbols that indicates the chemical composition of a substance.

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Groups

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In the periodic table are the elements which have the same number of electrons in their outer shells and so have similar chemical properties. Elements all lie in same column in the periodic table.

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Ion

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This is a charged particle formed by loss or gain of electrons. When atoms lose an electron they become a positive one of these. When they gain an electron they become a negative one of these.

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Ionic bond

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A bond that forms between two atoms when an electron is transferred from one atom to the other, forming a positive-negative ion pair.

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Ionic Compound

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A compound which occurs when a negative ion (an atom that has gained an electron) joins with a positive ion (an atom that has lost an electron): The ions swap electrons to achieve a full outer shell.

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Isotopes

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Atoms of the same element that have different numbers of neutrons are called isotopes.

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Lattice

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This is a regular grid-like arrangement of atoms in a material.

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Lubricant

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A substance used to reduce the friction between two solid surfaces.

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Malleable

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If a material is this, it is capable of being hammered or pressed out of shape without being likely to break or return to the original shape.

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Mass

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This is a measure of the amount of material in an object. It is measured in grams (g).

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Mass Number

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In an element this is the number of protons plus the number of neutrons in the nucleus of the atom.

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Molecular Compound

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This is made up of at least two different elements, which share electrons to form covalent bonds.

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Molecule

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This is a collection of two or more atoms held together by chemical bonds. It is the smallest part of a substance that displays the properties of the substance.

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Molten

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This means reduced to liquid form by heating. It is mainly used to describe rock, glass or metal.

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Negligible

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So small as to be not worth considering.

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Nucleus

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Found at the centre of an atom, it contains protons and neutrons.

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Neutron

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This is a particle that is found in the nucleus of an atom, has a mass approximately equal to that of a proton, and has no electric charge.

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Product

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This is a substance formed in a chemical reaction.

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Protons

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This is a small particle with a positive charge found in the nucleus of the atom.

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Reactant

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This is a substance put together with another substance/substances to undergo a chemical reaction.

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Relative Mass

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This is the number of times heavier a particle is, compared to another.

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Stable

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Atoms are this if their outer shell contains its maximum number of electrons.