atomic structure and the periodic table. notes: write down important vocabulary words as we go...
TRANSCRIPT
Atomic structure and the Periodic Table
Notes: Write down
important vocabulary words
as we go through today’s Power Point.
Review:Subatomic Particles as listed in a
block on the period table.
Proton: p+, positively charged particle, in nucleus.
Neutron: no, no charge , in nucleus.
Electron: e-, negatively charged particle, in electron levels, filled by lowest energy levels first with a max pair in each energy level.
Atomic number = the number of protons.
Average Atomic mass = the number of protons plus the
average number of neutrons in the nucleus.
Isotopes – atoms of an element with differing amounts of
neutronsThe average atomic mass is the average mass of a mixture of isotopes that occur in nature.
Ions – atoms of an element with differing amounts of electrons.
If electrons do not equal protons, we call it an ion, not an atom.
Ions will have a positive or negative charge.
Do not confuse ions and isotopes. Ions –different amounts of
electrons.
An atom has no charge so there is an equal number of electrons and protons. Remember that the mass is the total number of neutrons and protons.
Bohr Modeling:Bohr Models are one of the most used models. Even though the orbit shapes are not correct, the
model is very useful and explains most chemical behavior.
Bohr Models
The Bohr Model of the Atom One of the simplest working
models of the atom is that developed by Niels Bohr. In this,
a central nucleus containing protons and neutrons is orbited by electrons. The electrons are arranged in shells or energy
levels.
Bohr Model:1. Nucleus in the center with protons and neutrons.2. Electrons in different orbit levels.3. Larger Orbits represent electrons with more energy.
Electrons in shells nearer the nucleus have lower energy than
those farther away.
Today’s model of an atom is a dense positively charged nucleus surrounded by a negative cloud of
electrons and is based on probability
Electron cloud - the region around the nucleus of an atom
with a 90% or high probability of finding an electron
Periods – there is a period for each electron level.
1st electron level only has 2 atoms.
2nd electron level only has 8 atoms.
3rd electron level has 18 atoms.
1s1
2s2 2p6
3s2 3s63d10
1s2
Groups or Families: Up and Down
Have Similar Properties.
Look at back of book, on top of Group for group name.
Left side is group 1 or 1A.
US uses number 1, Europe uses 1A.
Right side is group 18.
Left Group 1 is called Alkali Metals.
Left 2nd Group 2 is Alkaline Earth Metals.
Rightmost Group 18 is Noble Gases.
Electron Dot Structure
Electron dot structure = represent the electrons in the outermost
shell
Never more then 8 dots, these dots will allow us to predict how
the element reacts
How many dots would go around these atoms?
Cl
Li
Na
Mg
C