Download what is the atomic number?

September 14, 2011
___________________Chemistry Atomic Structure Notes___________
 what are the subatomic particles of an atom?
a. proton --positive charge, found in nucleus, dictates identity of
atom, mass 1 amu
(amu -- atomic mass unit)
b. neutron-- no charge, found in nucleus, mass of 1 amu (job is to
add mass to atoms
c. electron-- negative charge, found in orbits outside of nucleus,
mass is extremely small (job is chemical bonding)
 what is the atomic number?
the number of protons in the atom
 what is the mass number?
the number of neutrons and protons in the nucleus of an atom.
 how do I find the number of neutrons?
take the mass number and subtract the number of protons
 how do I find the number of protons?
look at the atomic number
 how do I find the number of electrons?
look at the atomic number (protons). In a neutral atom, the
number of electrons will be the same as the number of protons
 what is the nuclear symbol?
The symbol from the periodic table for the element, with the
atomic number on bottom and the mass number on top.
***complete the "What's in the Atom?" worksheet in PENCIL. We will
discuss isotopes and ions tomorrow and talk about the (+1, -1, -2, and
+2) on the worksheet then. We will also discuss why the mass
number is not exactly like the atomic mass on the Periodic Table. For
today, use the mass number on the worksheet under nuclear symbol
when figuring mass number and neutron column information.*****
****if I have not already given you a periodic table, you may borrow
one today from my desk, make sure to return it at the end of class.
have a great day.****