Mid Year Science Review
Chemistry,Earth History,Infectious Diseases
Periodic Table
A table of the chemical elements arranged in order of atomic number, usually in rows, so that elements with similar atomic structure appear in vertical columns.
Atomic Number,Atomic Mass
The mass number, also called atomic mass number or nucleon number, is the total number of protons an neutrons in an atomic nucleus.
Protons & Neutrons & Electrons
Atoms are the basic units of matter and the defining structure of elements. Atoms are made up of three particles protons, neutrons and electrons. Protons and neutrons are heavier than electrons and reside in the center of the atom and which is called the nucleus.
Groups & Periods
A period is the name given to a horizontal row of the periodic table. The periodic table has seven periods.
A group is a column of elements in the periodic table of the chemical elements.