Atomic Structure -- by Ria Park

Atomic Structure


Subatomic Particles

• Neutron = Large with no charge; location=nucleus
• Proton = Large with positive charge; location=nucleus
• Electron = small with negative charge; location=cloud surrounding the nucleus - A neutral atom has no overall net charge.

    Atomic Number: The Proton Number

• found in the nucleus of an atom
• has no overall electric charge

Atomic Number = # of protons - # of electrons

Ions

• Atoms that have gained or lost electrons are called Ions
• Most atoms are capable of either gaining or losing electrons. A few elements, like hydrogen, are able to do both -- by accepting electrons from or giving electrons to, either atoms.
• An ion is an electrically charged atom.
• Negatively-charged ion: anion = when electron are added to a neutral atom
• Positively-charged ion: cation = when electron are subtracted to a neutral atom

Mass Number

• is the number of protons and neutrons or atomic mass number since atomic # = the # of neutrons
• Atomic mass ≠ # of protons + #of neutrons
• Number of neutrons = Mass number - protons

Atomic Mass

• The average mass of an element's isotopes
• since most of the mass of an atoms is concentrated in the protons and neutrons located in the nucleus.
• If a neutron is added to an element's nucleus, a heavier version of the same element (isotope) will be produced.

Isotopes

• are atomic species having the same atomic number (protons) but different atomic masses/mass numbers (neutrons)