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Atoms, Elements, and the Periodic Table. Online Periodic Tables. If you need to use a periodic table while at home, try these: http://www.chemicool.com/ http://periodic.lanl.gov/default.htm NC DPI (official one for Science EOG):
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Online Periodic Tables • If you need to use a periodic table while at home, try these: • http://www.chemicool.com/ • http://periodic.lanl.gov/default.htm NC DPI (official one for Science EOG): • http://www.ncpublicschools.org/docs/accountability/testing/eog/science/2009grade8periodic.pdf
PART 1: ATOMS • What are atoms made of? NUCLEUS – center of the atom PROTON (+) NEUTRON (0) ELECTRON (-) – surrounds the atom in a cloud.
An Atom – DON’T DRAW THIS ONE NUCLEUS ELECTRONS PROTON NEUTRON
PROTONS • Positively charged particle • Found in nucleus of an atom • Same as the atomic # • Tells what kind of atom it is, the specific element. For example – hydrogen, oxygen, sodium, gold
NEUTRONS • Neutrally charged particle (no charge) • Found in nucleus of an atom • Tells what version (isotope) of the element it is
ELECTRONS • Negatively charged particle • Found outside of the nucleus • They surround the nucleus in a cloud because we don’t know exactly where they are at any given time • Much smaller than protons and neutrons • Usually equal to the protons
Most of the atom is taken up by the space between the nucleus and the electrons.
ELEMENTS • ELEMENT = A specific kind of atom. Determined by the number of protons (atomic #) ATOM = generic (car) ELEMENT = specific (Porsche 911 or Ford Edge etc) • Every atom of an element has the same number of protons. For example – every Lithium atom always has 3 protons
ATOMIC NUMBER = the number of protons in an atom. This tells you what kind of element it is. • ISOTOPE = Atoms with the same number of protons and a different number of neutrons. • MASS NUMBER = The sum of the protons and neutrons in an atom. This is how you identify the isotopes. • ATOMIC MASS = the average mass of all the isotopes of an element
Dmitri Mendeleev was the first person to organize the elements. He made the first periodic table. • He organized it in order of increasing atomic mass. We don’t do it this way any more. • CHEMICAL SYMBOL = a short way of telling what the chemical is. It’s usually 1 or 2 letters. EXAMPLES: Barium = Ba Tungsten = W
1 2 3 mass mass mass + + 3 • ATOMIC MASS = the average mass of an element. This includes all the isotopes of that element.
The elements in today’s Periodic Table are arranged by their atomic number. • A PERIOD = a horizontal row in the periodic table. There are 7 of them. • Elements in a period change from left to right according to a pattern. There is a trend that the elements follow.
A GROUP = A vertical column on the periodic table. Also called a FAMILY. There are 18 of them. • Elements in a group all have similar characteristics. Groups are often named for the top element in the column. EXAMPLE: Carbon group Nitrogen family
12 Mg Magnesium 24.305 ATOMIC NUMBER CHEMICAL SYMBOL CHEMICAL NAME ATOMIC MASS
# of Protons = # of Electrons = # of Neutrons = Atomic Number = Mass # = Element Name = Group # Period #