Atomic Structure Atoms are made of 3 subatomic particles: proton, neutron, electron NAME WHERE ELECTRIC SIZE IMPORTANCE FOUND CHARGE Protons Nucleus Positive (+) 1 amu Determines the identity of an element Number of protons is the atomic number Neutrons Nucleus No Charge 1 amu Determines (w/ protons) the mass of the atom Electrons Somewhere Negative (-) 1/1836 amu Determines how atoms in the reacts with other Electron atoms Cloud-exact Each energy level in the location electron cloud can hold unknown a limited # of electrons

Atoms AMU = Atomic Mass Unit. It is the size of a proton. It takes 600,000,000,000,000,000,000,000 protons to make 1 gram. Atoms are electrically neutral. This is because an atom has the same number of protons (positive charges) as electrons (negative charges)

Chemical Symbol An abbreviation that represents the name of an element The chemical symbol can contain 1 or 2 letters. The first letter is always capitalized. The second letter is lower cased. Ex.: Hydrogen = H Silicon - Si

Atomic Number Remember: Make an A+, you’re #1! Atomic number is the number of protons in an element. It identifies the element. If you change the number of protons, you change the element.

Mass Number Mass Number- Equal to the number of protons + the number of neutrons in an atom. MASS NUMBER = # PROTONS + # NEUTRONS We can use the mass number to find the number of neutrons an element has. To find the number of neutrons in an atom, subtract the atomic number from the mass number. # NEUTRONS = MASS NUMBER - ATOMIC NUMBER

Atomic Mass Atomic Mass: The average mass of all known isotopes of an element. This is found on the periodic table. Isotopes are the elements that have atoms with different numbers of neutrons, so a different mass number

H Isotopes H H H Mass Number 2 1 Chemical Symbol Atomic Number Ex.: Hydrogen Isotopes 1 3 1 H H H 2 1 Isotope Name Protium Deuterium Tritium (Hydrogen-1) (Hydrogen-2) (Hydrogen-3) Mass Number *Because the mass number is different for each isotope of hydrogen, the number of neutrons in each atom is different. The number of protons, however, is the same.

Reading an element tile on the periodic table Copy Tile and Labels Atomic Number (Number of Protons & Number of Electrons) 11 Na Sodium 22.990 Chemical Symbol Element Name Atomic Mass (Average Mass of All Known Isotopes)

Atoms and APEMAN APEMAN = A way to remember all parts of an atom A = Atomic Number P = Protons E = Electrons M = Mass Number -A = Atomic Number N = Neutrons

Atoms and APEMAN Example: Sodium-23 P = Protons 11 E = Electrons 11 A = Atomic Number 11 P = Protons 11 E = Electrons 11 M = Mass Number 23 -A = Atomic Number -11 N = Neutrons 12

Copy and Complete the Table Below Isotope Name Isotope Symbol Atomic Number Mass Number #P #N #E Iron- 56 16 K 39

Copy and Complete the Table Below Isotope Name Isotope Symbol Atomic Number Mass Number #P #N #E Iron- 56 56 Fe 26 30 Sulfur- 32 32 S 16 Potassium- 39 39 K 19 20