The Atom

Subatomic particles are distinguished by charge and location

Nucleus Outside the nucleus Inside the nucleus Electrons: Cloud of very tiny, negatively charged particles Mass of electrons is much smaller than that of a proton or neutron Inside the nucleus Protons with a positive charge Neutrons with no charge Protons and Neutrons are almost identical in size and mass

Number of Protons Each element has a unique number of protons Elements are defined by the number of protons in an atom of that element. Most atoms don’t have an overall charge Most atoms have an equal number of protons and electrons. The charges cancel

IONS If an atom gains or loses electrons, it becomes charged. Charged atoms are called Ions Gain: - Lose- +

ATOMIC NUMBER & ATOMIC MASS Atomic Number: The number of protons Atomic Mass: Total number of particles in the nucleus. (Protons & Neutrons)

ISOTOPES Same number of protons but different number of neutrons relative to other atoms of the same element

CALCULATING THE NUMBER OF NEUTRONS

ACTIVITY Groups of 2 Pick any element on the periodic table Info needed: Atomic Number, Atomic Mass, number of Protons and number of Neutrons Make a SHORT story (1-2 paragraphs) about your element. Include all the information above! Be creative!