Transcript Science Fair Project

Basic Chemistry
What you may or may
Not have learned in
8th grade science…
Atomic Structure
Within the nucleus of the atom:
Protons - +1 charge
Neutron - 0 charge
Outside the nucleus
Electrons - -1charge
Where are these Atoms
Periodic Table of Elements
96% of life’s
elements are
HONC –
99% =
CHNOPS
Close look at elements
Atomic Weight = The mass of the
nucleus of the
atom
Atomic Number = The number of
protons
How to Draw Out Electron Shells
More about elements
 Isotopes
 Have more neutrons HOWEVER behave the same
as the original because the protons and neutrons
still balance each other out
 Ions
 Have one extra or one less electron
 Carbon 13 or Carbon 14 (which is radioactive and
used in research)
 Molecules vs. Compounds
 2H + O
H2O
1 molecule of water or a compound
reactants
products
All are molecules
Compound – two
or more elements
bonded together
Bonding
COVALENT BONDS – sharing of electrons between atoms
Non polar – electrons are equally shared
Polar – electrons are not equally shared (electrons get pulled
towards a higher electronegative molecule
Water is polar covalent bonding
More Bonds
 Ionic Bonds – one
atom pulls the
electron away from
the other atom
 Opposite charges
attract each other
Perhaps one of you gentlemen would mind telling
me just what is outside the window that you find so
attractive...?"
Bonds Between Compounds
Dipole - Dipole – forms weak
bonds to make a new compound
(while keeping the original
intact) involves attaching the
positve end to the negative end)
Hydrogen Bonds – hydrogen
covalently bonded to one atom
will also be attracted to one
another - 20x weaker then
covalent bonds
Water Chemistry
We just saw that Hydrogen Bonding effects water…
It is a polar molecule - a positive and negative end
…
Water is cohesive – H bonds holding it together –
that’s how water gets up a plant
Water is adhesive – water will cling to other
substances as well (meniscus)
Surface Tension – at the interface between water and
air is a highly ordered arrangement of molecules