Science Periodic table and atomic structure T2

element

a pure substance made of only one type of atom (like oxygen or gold)

compound

a substance made when two or more different elements chemically combine (like water H20)

mixture

a combination of substances that are physically mixed but not chemically joined (like trail mix or salt water)

alloy

a mixture of metals (or a metal with another element) made to improve strength or other properties

metal

an element that is usually shiny, conducts heat and electricity, and can be bent or shaped

non-metal

an element that is usually dull, does not conduct heat or electricity well, and may be brittle or a gas.

metalloid

an element that has properties of both metals and non-metals (like silicon)

physical property

a characteristic you can observe or measure without changing the substance (colour, density, melting point)

chemical property

a characteristic that describes how a substance reacts to form new substances (like burning or rusting)

reactivity

how easily a substance reacts with other substances

atom

the smallest unit that still has the properties of that element

atomic model

a scientific drawing or idea that shows what scientists think an atom looks like

proton

a positively charged particle found in the nucleus of an atom

neutron

a particle with no charge found in the nucleus of an atom

electron

a negatively charged particle found orbiting the nucleus in shells

atomic number

the number of protons in a neutral atom (this identifies the element

mass number

the total number of protons and neutrons in an atom

nucleus

a centre of the atom that contains protons and neutrons

electron shell

a region around the nucleus where electrons are likely to be found

periodic table

a chart that organises all known elements by atomic number and similar properties

group

a vertical column on the periodic table , elements in a group have similar properties

period

a horizontal row on the periodic table, elements in a period have the same number of electron shells

valence electrons

the electrons in the outer shell of an atom that are involved in bonding

atomic radius

the size of an atom (distance from the nucleus to the outer shell)

ion

an atom that has gained or lost electrons and now has a charge

symbol

a one or two letter abbreviation used to represent an element

periodic trend

a pattern in how properties change across rows or down columns of the periodic table

isotope

when the atom has a neutron number different to the number of protons