Download Elements Water and pH

Elements, Water and pH
Chemistry of Life
All matter is composed of tiny particles called atoms.
There are 109 types of atoms. A substance made
up of one kind of atom is called an element.
An atom is the smallest part of an element that still
has the properties of that element.
A is for Atom
https://www.youtube.com/watch?v=Oc2s9q
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CHNOPS
Molecules and Compounds
When two or more atoms bond, they form
a molecule.
A compound is a substance made of 2 or
more different elements
In Your Notes…
How is it that two atoms can make a
molecule but not a compound?
Why do elements bond?
• Elements bond(stick together) because of the structure
of their electrons.
• If the outer ring of electrons is not full with 8 total
electrons, the atom will bond to complete it’s outer ring.
(Hydrogen’s outer ring is full with 2)
Ionic Bonds
Ionic Bonds are formed when atoms lose
or gain electrons and become electrically
positive or negative.
The resulting opposite charges a drawn to
each other.
Covalent Bonds
Formed when atoms “share electrons”
How many drops of water fit on a Penny?
 Have every person in
your lab group estimate
how many drops of water
can fit on the top of a
penny before it spills over
the edge and gets the
paper towel wet.
 Test it to see who was
the closest to the correct
answer.
Polar Molecules
 Water is a “Polar Molecule”
because it has a positive and
a negative side to it.
 Because the electrons from
the Hydrogen atoms are stuck
in bonds with the Oxygen, the
Hydrogen side becomes
positive and the Oxygen side
becomes negative.
Water is the “Solvent of Life”
Because of
water’s polarity, it
breaks ionic
bonds to form
solutions.
Characteristics of Water
 Because water is “polar”
it has the following 2
characteristics.
Cohesion-water molecules
stick to each other
Adhesion- water molecules
stick to other substances.
Non-polar Molecules
Non-polar molecules have the same
charge all the way around. There are no
“poles”
All lipids are non-polar
Oil and Water do not mix!
 The cell membrane forms
because phospholipid molecules
are polar(hydrophilic) on one
end and nonpolar(hydrophobic)
on the other end.
pH or Hydrogen Ion to Hydroxide Ion ratio
The pH scale is a scale from 1 to 14. a pH
of 7 is “balanced” or neutral.
A pH below 7 is acidic and above 7 is
alkaline or basic.
Acids have more hydrogen Ions than
Hydroxide ions.
Bases have more Hydroxide ions than
Hydrogen Ions.
The pH Scale
pH explained
http://www.youtube.com/watch?v=Xeuyc55
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