science glossary terms

The smallest particle of an element that retains the identity of the element.

• A negatively charged (-) particle within the atom.

• A subatomic particle is a particle that is smaller than the atom.
• eg. electron, proton, neutron

• The nucleus is the center of the atom
• It is positively charged (contains only protons and neutrons)
• The negatively charged electrons revolve around the nucleus in the different energy levels.

The proton is a positively charged particle that is part of every atomic nucleus.

• The neutron is an uncharged particle that is part of almost every atomic nucleus.

The atomic number is the number of protons in the nucleus of an atom

The mass number is the number of protons and the number of neutrons in the nucleus of an atom.

• the isotope is one of two or more forms of an element that have the same number of protons but a different number of neutrons.
• eg. hydrogen -1 has 1 proton, 
• while hydrogen- 2 has 1 proton and one neutron

The bohr model shows a positively charged nucleus in the center, and negatively charged electrons throughout the different energy levels.

The atomic mass is the average mass of the naturally occuring isotopes of an element.

• # of neutrons = mass number - atomic #
• eg. flourine   
•                      n^o = 19 - 9
•                          = 10

A system for organising the elements into columns and rows, so that elements with similar properties are in the same column.

• Typically an element that is hard, shiny, malleable, and ductile, and is a good conductor of heat and electricity.
• eg. titanium, alluminum, iron

• An element that is not shiny, malleable, or ductile, and is a poor conductor of heat and electricity.
• eg. some gasses and some liquids (except bromine, which is a liquid) carbon, nitrogen, oxygen.

• An element that shares some properties with metals and some properties with non- metals.
• eg. boron, silicon, arsenic.

A period is a horizontal row of elements in the periodic table.

A group is a verticle column of elements in the periodic table.

• alkali metals are metals that are highly reactive.
• group 1 on the periodic table.
• these metals have low melting points.
• usually stored in kerosene or oil to keep oxygen away.

• found in group 2 on the periodic table.
• highly reactive, but less so that group 1.
• if heated, they will burn in air -produces bright colorful flames eg. used in fireworks

• found in group 17 on the periodic table.
• highly reactive and corrosive.

eg. flourine, chlorine, bromine

• found in group 18 on the periodic table.
• odourless, colourless gasses.
• noble gasses are non reactive

An electron in the outermost occupied energy level of an atom.