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The Nature of Matter
The Atom
• Extremely small – 100 million = 1
centimeter
• Subatomic particles
– Proton - positive
– Electron - negative
– Neutron - neutral
Elements
• Pure substance that consists entirely of
one type of atom
Isotopes
• Atoms of same element that differ in the
number of neutrons they contain
• Radioactive:
– Nuclei are unstable
– Break down at a
constant rate
Used for fossil dating
Chemical Compounds
• Substance formed by 2 or more elements
– Ex. Water H2O, NaCl
Chemical Compounds
• A force that joins atoms together is called
a chemical bond
• Every compound is represented by a
chemical formula that identifies the
elements in the compound and their
proportions
– H2O
– H2O2
Electron configuration
• Electrons are found in orbitals around the
nucleus
• Follows the octet rule
– 1st orbital (or shell) max electrons = 2
– 2nd orbital – max electrons = 8
– 3rd orbital – max electrons = 8
Chemical Bonds
• Valence electrons – those electrons available
to form bonds (outer most electrons)
• Ion – charged particle
• Ionic bond – one or more electrons are gained
or lost (ex: salt)
– Lose electron – become +
– Gain electron – become -
Covalent Bonds
• Atoms share electrons to fill outer shell
• Molecule – atoms joined by covalent bonds
– Smallest unit of most compounds
Covalent Bonds
• An element becomes stable when its outer
electron level is full
• Give two examples of molecules formed
from covalent bonds:
– carbon dioxide
– water
Other Bonds
• Hydrogen bonds- a weak chemical
attraction between polar molecules
– Ex: water molecules
Other Bonds
• Van der Waals forces- slight attraction
between oppositely charged regions of
nearby molecules (ex-gecko feet)
– Not as strong as ionic or covalent bonds
Water
• Water is a major component of cells
• Nearly 80% of your body is made of water
• What properties of water make it such an
important substance for life?
– Water stores heat efficiently
– Water sticks to itself and other substances
Water
• Is a polar molecule
– Due to its electrons being shared unequally
– The oxygen has a much stronger pull on the
electrons than the hydrogens do
– We can show this with (+) and (-)
Polar- Magnets
Polar vs Nonpolar
• Polar substances mix together (water)
• Nonpolar substances mix together (oil)
• Polar and nonpolar substances do not mix
together (water and oil)
Water- Hydrogen bonding
• Due to slight negative and positive
charges
• Gives water many of its unique properties
(cohesion)
– Allows it to “stick” together
– forms droplets and thin film
– Surface tension
– Bugs can walk on it
Hydrogen Bonds
Cohesion
• Attraction between molecules of the same
substance
• When like substances stick together
– Water to water
Adhesion
• Attraction between molecules of different
substances
• When different substance stick together
• Ex- Glass and water- meniscus
• Causes some things to get wet
Capillary Action
• Water moving up through a small tube
• Adhesion- allows the water to stick to the
sides of the tube
• Cohesion- allows the water molecules to stick
together while climbing
– Ex: girls going to the bathroom as a group!!
– Ex: water going up a plant from the roots
Capillary Action
Heat Capacity
• Because of the multiple hydrogen bonds
water requires a lot of energy to heat up
• Regulates temperature in
• Ocean and lakes
• Cells
• Boiling water
• How long does it take?
• When can you touch it?
Mixtures
• Material composed of two or more
elements or compounds that are physically
mixed together but not chemically
combined
• Two types that involve water
– Solutions
– Suspensions
Solutions
• Solute- what is being dissolved (Koolaid
powder)
• Solvent- what the solute is being dissolved in
(water)
• Solute + Solvent = Solution (Koolaid)
Water as a Solvent
• Water is the universal solvent
• Because it is polar it can dissolve
– Other polar substances
– Ionic compounds
– Salts
– Sugars
– Minerals
– Gases
– Even other solvents such as alcohol
Water as a Solvent
• Saturated Solution- the water can’t dissolve
any more solute
Suspension
• A mixture of water and non-dissolved
material
• Some materials do not dissolve when
placed in water, but separate into pieces
so small that they do not settle out
– Ex: blood
pH Scale
• pH stands for potential hydrogen, 0-14
pH Scale
• Measure the concentration of H+ (hydrogen
ions)
• Above 7 is basic
• 7 is neutral
• Below 7 is acidic
Neutral
• Has equal numbers of H+ and OH• Ex: water
Basic
• A base is a compound that produces
hydroxide (OH–) ions in solution.
• Ex: baking soda
• Has more OH- than H+
• The closer to 14 the stronger
• The closer to 7 the weaker
• Usually end in -OH
Acids
• An acid is any compound that forms H+ ions in
solution.
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Ex: orange juice, HCl (stomach acid)
Has more H+ than OHThe closer to 0 the stronger
The closer to 7 the weaker
Usually begin with H-
Buffers
• Keep solutions from becoming two acidic or
basic
• Weak acids or bases
• Essential in maintaining homeostasis
• The pH of the fluids within most cells in the
human body must generally be kept between 6.5
and 7.5
Buffers
Carbon
• Has 4 valence electrons
• Forms covalent bonds
• Makes up organic compounds
• Can bond with
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Hydrogen
Oxygen
Phosphorus
Sulfur
Nitrogen
Carbon
• Can bond to each other
– Single
– Double
– Triple
Macromolecules
• Giant molecules
• Made from monomers (single unit)
• Polymer- many monomers
Organic Macromolecules
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Carbohydrates
Lipids
Proteins
Nucleic Acids
Carbohydrates
• Organic compounds made of carbon, hydrogen
and oxygen in a proportion of 1:2:1
• The building blocks of carbohydrates are called
monosaccharides
• Glucose is a major source of energy for cells
• Give an example of a food that contains
carbohydrates: pasta, bread, potatoes
• Structural in plants- cellulose
Carbohydrates
• Sugars
• End in –ose
• Plants store energy
– starches
Carbohydrates
• Monosaccharide- Single sugar
– Glucose, galactose, fructose
• Disaccharide- two sugars, table sugar
• Polysaccharide- many sugars, glycogen
Lipids
• Important part of the structure and functioning of
cell membranes
• Examples of lipids: waxes, fats, steroids, oils
• Lipids that store energy are called fat
• Give an example of a food that is a lipid: butter
• Natural waterproofing
Saturated vs Unsaturated
Saturated vs. Unsaturated
• Saturated
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Normally animal based
Solid at room temperature
No double bonds between carbons
Ex- butter
• Unsaturated
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Normally plant based
Liquid at room temperature
At least one double bond between carbons
Ex- corn oil
Proteins
• Made of nitrogen, hydrogen, carbon, and
oxygen
• Polymers made of monomers called amino
acids
• 20 amino acids
• Peptide bonds link these monomers (type of
covalent bond)
• Give an example of a food high in protein: meat,
fish, eggs, nuts
Functions of Proteins
• Enzymes - control the rate of reactions and
regulating cell processes
• Forming cellular structures
• Transporting substances into or out of cells,
• Helping to fight disease.
• Where is it found? Skin, bones, ligaments,
tendons
• The most abundant protein in your body is
collagen
Levels of Protein Organization
• Four levels
– Primary- sequence of amino acids (polypeptide)
– Secondary- folding or coiling of the polypeptide
– Tertiary- 3-d arrangement of polypeptide
– Quaternary- made up of more than one
polypeptide
Levels of Protein Organization
Nucleic Acids
• Made up of nucleotides (monomers)
• Each nucleotide has three parts:
– sugar
– base
– Phosphate group
• Joined by covalent bonds
Nucleic Acids
• There are two nucleic acids :DNA and RNA
• DNA consists of 2 strand(s)
• Sugar- deoxyribose
• RNA consists of 1 strand(s)
• Sugar- ribose
Nucleic Acids
• Store and transmit genetic information
• Made of hydrogen, oxygen, nitrogen,
carbon, and phosphorus
ATP
• Carries energy for cells
• When food is broken down some of the energy
in the molecules is stored temporarily in ATP
Energy
• Organisms need energy for life processes
• Forms of energy
– Light, heat, electrical, mechanical, chemical
• Energy can be absorbed or released by
chemical reactions
– Reactions that release energy can occur
spontaneously (burning)
Chemical Reactions
• Process that changes, or transforms, one set of
chemicals into another by changing the chemical
bonds that join atoms in compounds
• Reactants- elements or compounds that enter
into a chemical reaction
• Products- elements or compounds produced by
a chemical reaction
Chemical reactions absorb or release
energy
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If bonds are formed energy is absorbed
If bonds are broken energy is released
When water freezes heat energy is released
When ice melts heat energy is absorbed
When food is digested chemical reactions
convert chemical energy into a form cells can
use
Energy Sources
• Animals- eat food
• Plants- photosynthesis, sunlight
Energy is needed to start
a chemical reaction
• The energy needed to start a chemical reaction
is called activation energy
• Activation energy is like a chemical “ push”
• Is activation energy needed in a reaction that
releases energy? Yes!
Catalyst
• Some chemical reactions are too slow or
have activation energies that are too high
to make them practical for living tissue
• Substance that speeds up the rate of a
chemical reaction
– Work by lowering a reaction’s activation
energy
Enzymes help reactions occur
• Natural catalysts
• Enzymes increase the speed of chemical
reactions
• Most enzymes are proteins
• Enzymes are catalysts that reduce the activation
energy required to start a chemical reaction
• Enzymes help organisms maintain homeostasis
• Named for the reaction it catalyzes
• Ends in -ase
Effect of Enzymes
Enzymes affect specific substances
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Enzymes act only on specific substrates
This is because only that substrate fits
into its active site
List the three steps of enzyme action:
1) Enzymes attaches to substrate at active site
2) The enzyme changes the shape of the
substrate reducing the activation energy
needed to start the reaction
3) The enzymes detaches from the substrate
Factors that affect enzyme activity
• Any factor that changes an enzyme’s
shape will affect its activity
• List two of these factors:
1) pH
2) temperature
• Enzymes in the human body works best
around 37 degrees Celsius