Download H - Shelton School District

Chemistry of Life
Atoms
Greek for “indivisible”
Smallest possible particle of an
element
Made up of
Proton (+)
Neutron(=)
Electron(-)
Nucleus= central core of atom made
up of proton and neutron
Surrounded by electrons
2
Protons
2
Neutrons
2
Electrons
Helium atom
Elements
Determined by the number of protons in the
atom
All atoms of that element have the same
number of protons
Atomic number= number of protons
Number of electrons and neutrons is not
always consistent.
Periodic table is set up to show an element
based on it’s atomic mass and the number of
electrons in it’s outer shell.
Isotopes
• An Isotope is an element with a different number of
neutrons than protons
• Ex: Carbon 12, Carbon 13, Carbon 14
• radioactive isotope: an isotope where the nucleus
decays over time giving off radiation
Electrons
•When an atom is left
alone the electrons
equal the protons
•Many atoms will
lose or gain one
electron in bonding
•Electrons in the
highest energy level
(valence electrons)
determine how it will
interact with other
atoms.
Electrons
Outermost electron shell (can hold 8 electrons)
Electron
First electron shell (can hold 2 electrons)
Hydrogen (H)
Atomic number = 1
Carbon (C)
Atomic number = 6
A bond that occurs when
an atom transfers an
electron to another
atom.
EX: NA- CL
Sodium gives an
electron to chlorine
NA+ & ClNaCl
This leads to Ions
Ion= an atom that has
become electrically
charged (+ or-)
Ionic Bonds
Covalent Bond
A bond that forms
when two atoms share
electrons.
The number of bonds
that can be formed is
determined by the
number of electrons
needed to fill the
highest outer level
Molecules
A molecule is two or more atoms
held together by a covalent bond.
Chemical Reaction
The breaking of old and forming of new
bonds to make new chemical
substances.
Reactant: The starting materials
Product: The ending materials
Reactants
Product
Water properties
Water
All living things are dependent on water
Cells are 70% to 95% water
Water is the only compound found on earth
in all 3 forms
Water is one oxygen covalently bonded to
two hydrogen's.
Although this is a covalent bond the oxygen
pulls the shared electrons closer to itself
making it more negative and making the
hydrogen more positive.
Water properties
Oxygen has 6 electrons in it’s highest shell. It wants to have 8
Hydrogen has only one electron in it’s outer shell, it wants 2.
They share their electrons allowing for oxygen to gain 2 to make
8 and hydrogen each gets one making it 2.
Oxygen has 8 protons in it’s nucleus and this then makes it pull
the electrons closer to make the atom neutral.
This pull is why water is considered polar and slightly misshapen
The slight polarization of water leads to hydrogen bonds where
they are attracted due to polarization not electron sharing or
trading.
Water structure
Waters life-supporting properties
Cohesion: The
tendency of
molecules of the
same kind to stick to
one another.
Adhesion:
Attraction that
occurs between
unlike molecules.
Important in plants
because as water
evaporates it pulls
itself upward in
plants.
Important because
water sticks to the
sides of the plant
tubes and helps
combat gravity.
Waters life-supporting
properties
Temperature moderation: Water has a
very strong ability to resist change in
temperature due to hydrogen bonding
between molecules
Water allows for temperature
regulation of the world by staying
cool in the summer and warm in the
winter
Waters life-supporting properties
Ice: the solid form of
water that is lower density
than the liquid form. As
water freezes the
molecules move further
apart.
Important because it
allows animals to continue
to live under frozen water
instead of being frozen
from the bottom up.
Waters life-supporting properties
Water has a great ability to dissolve other
substances.
Water is the universal solvent
Solvent: The substance that dissolves
another substance
Solute: The substance that is being
dissolved
Solution: A uniform mixture of two or
more substances.
Acids, Bases, Buffers,
Ph
Ph Scale
Water sometimes breaks into ion’s of
H+ and OHHydrogen ion(+) and Hydroxide ion(-)
These ions are what determine whether
something is an acid or base.
The Ph scale is an exponential scale
showing acids and bases. (power of 10)
Ph Scale
Scale from 0 to 14
each step is 10x
more than the
next
0-6 is Acidic
7-8 is neutral
8-14 is Basic
LE 2-15
pH scale
H+
H+
H+

H+ OH
+
OH H
H+
Lemon juice, gastric juice
H+
H+
Grapefruit juice, soft drink
Acidic solution
Tomato juice
Human urine
OH
OH

H+
H+ OH

OH OH
H+
H+
H+
Neutral solution
NEUTRAL
[H+[

Pure water
Human blood
Seawater
Milk of magnesia
OH
OH
OH
Household ammonia
OH
H+
H+
OH
Household bleach
OH
Oven cleaner
Basic solution
Acids
An acid is any substance that gives
off H+ to the solution
Ex: lemon juice, stomach acid
pH scale
H+
H+
OH
H+

H+
OH
H+
H+
H+
H+
Acidic solution
Bases
A base is a compound that removes
H+ from the solution by giving off
OH- to bond with the H+
Ex: Soap, Bleach, Oven cleaner
Milk of magnesia
OH
OH
OH
Household ammonia
OH
H+
H+
OH
Household bleach
OH
Oven cleaner
Basic solution
Buffer
Cells are very sensitive to H+ and OH- ions.
Even a slight change in Ph will affect a cell.
A buffer will accept H+ ions when they are
too high and will donate H+ when they are
too low.
Blood is a great example of a buffer
Tomato juice
Human urine
OH
H+
OH

H+ OH

OH OH
H+
H+
H+
Neutral solution
NEUTRAL
[H+[

Pure water
Human blood
Seawater