Atoms

Particles of an Atom Atom: smallest amount of an element ParticleRelative Mass ChargeLocationOther Info Proton nucleusIdentifies the element Neutron 2000 No charge nucleusProton + Neutron = mass Electron 1 -Outside nucleus = number of protons

Electron Cloud Model Electrons don’t orbit the nucleus in a pattern Electrons dart around in energy clouds Each cloud has its own shape

Tom Lehrer’s Element Song

Energy levels of electrons Energy levels are “rings” around the nucleus Each level can hold a certain number of electrons – Level 1: up to 2 – Level 2: up to 8 – Level 3: up to 18 – Level 4: up to 32 – The outer energy level electrons have the most effect on the chemical properties of the element

Periodic Table of the Elements Atomic number Chemical symbol Element name Atomic mass

Atomic number Is the number of protons in an atom Is unique (identifies the element) Equals the number of electrons in a neutral atom In a Periodic table, the elements are arranged by increasing atomic numbers

Chemical symbol A notation of one or two letters that represent an element 1 st letter is always capital; 2 nd letter is always lower case – Examples: He, Al, Cu, Zn

Atomic mass Where is the mass of the atom? – Nucleus What particles are in the nucleus? – Protons & neutrons Atomic mass = number of protons + number of neutrons Atomic mass - # protons = # neutrons

Elements

Bellringer Use your periodic table to determine the number of neutrons in a carbon 18 isotope