Atoms: Subatomic Particles: Protons Protons have a positive charge. Protons are located inside the nucleus of the atom. Mass = 1 atomic mass unit (1 amu) Neutrons Neutrons have a neutral or “no” charge. Neutrons are located inside the nucleus of an atom. Mass = 1 atomic mass unit (1 amu) Electrons Electrons have a negative charge. Electrons are located outside the nucleus of an atom in the electron cloud. Mass = 0 atomic mass units (0 amu)
To find Protons, Neutrons & Electrons: A=P=E
M-A=N
A – Atomic Number P – Protons E – Electrons
M – Mass Number (round to nearest whole number) A – Atomic Number N - Neutrons
Chemical Symbols: A chemical symbol is an abbreviation of the name of a chemical element, such as N for nitrogen or Fe for iron. Chemical symbols can be one or two letters. Important: The 1st letter of the abbreviation is always a capital letter. The second letter is always lowercase.
Definitions: Atomic Number The atomic number is the number of protons in an atom; it distinguishes atoms of different element. Mass number The mass number is the total number of protons and neutrons in the nucleus of an atom.
How many electrons fit in each shell around an atom? 1
2
2
8
3
8
Elements and Compounds: Elements combine with each other to form molecules and/or compounds. Molecules can be like or different elements and
Compounds are different elements combined together. (E.g. Na + Cl = NaCl)