ch2 notes 2013
Post on 07-Nov-2014
493 Views
Preview:
DESCRIPTION
TRANSCRIPT
Chemistry of LifeChapter 2
2.1 Nature of MatterOrganisms are chemical machines All organisms consist of atoms
– Subatomic particles Electron (e-) – located in electron cloud Proton (p+) – located in the nucleus Neutron (no) – located in the nucleus
Oxygen atom (O)
Nucleus:8 protons (+)8 neutrons
outermost energy level: 6 electrons (-)
inner energy level: 2 electrons (-)
Elements– Differ in the number of protons in
the nucleus.– Number of protons = Number of
electrons Elements are neutral on the periodic table
– Atomic Number = Number of protons– Atomic Mass = Number of protons +
Number of neutrons
http://www.privatehand.com/flash/elements.html
Using the Periodic Table, Complete the following:
Name Symbol # p+ # e- #no
Tin
25
N
15
12
Isotopes Differ in the number of neutrons they
contain in the nucleus– Example:
Carbon 12 – 6p+, 6e-, 6no
Carbon 13 – 6p+, 6e-, 7no
Carbon 14 – 6p+, 6e-, 8no
Chemical Bonding – Compounds are made of joined atoms of two or more different elements.
Valence shell – outermost electron shell– Atoms with a full valence shell are inert
(unreactive)– Atoms without a full valence shell can form
bonds (reactive).
Complete the following table and answer the question in your notebook:
Name Symbol # p+ # e- #no
Oxygen
6
K
53
- Why do all isotopes of an element have the same chemical properties? (Use your book to help you answer this)
Bohr Atom Models The first electron shell of every atom
can hold a maximum of 2 electrons. Each additional shell can hold a
maximum of 8 electrons.
Draw the electron configurations of an atom of the following elements:
1. Fluorine
2. Boron
3. Sodium
Covalent bonds – atoms share electrons
– Ex: H2, O2, CO2
covalent bonds
Oxygen atom (O) Carbon atom (C) Oxygen atom (O)
Carbon dioxide (CO2 )
Ionic Bonds Ionic Bonds – atoms gain or loose
electrons– Atoms form ions + charge – cation - charge – anion
Ex: NaCl
2.2 Hydrogen Bonds Hydrogen Bonds – weak chemical
attraction between polar molecules– Water is a polar molecule because the
electrons of O and H are shared unequally.
Cohesion
2.3 Carbon Compounds• 70% of your body is made of water.• The remaining 30% is made up
mostly of organic compounds (Carbon-based molecules).– Carbon is a unique element because it
forms four covalent bonds and can form a lot of different structures.
Many carbon-based molecules are made of many small subunits bonded together.– Monomers are the individual subunits.– Polymers are made of many monomers.
Carbohydrates Key source of energy found in
most foods Fruits, vegetables, and grains
Made up of single sugars called monosaccharides.
Glucose, fructose
Disaccharides - two monosaccharides are joined
Sucrose (table sugar)
Polysaccharides – chains of three or more monosaccharides
Starch, cellulose, glycogen
Polymer (starch)
Starch is a polymer of glucose monomers that often has a branched structure.
Polymer (cellulose)Cellulose is a polymer of glucose monomers that has a straight, rigid structure
monomer
Lipids Nonpolar molecules not soluble in
water Fats, phospholipids (make up the cell
membrane), steroids (cholesterol), waxes Saturated fatty acids
Solid at room temperature Butter, lard, grease
Unsaturated fatty acids Liquid at room temperature Olive oil, fish oil
Proteins Formed by chains of linked amino
acids Many functions including:
Enzymes Structural (imbedded in the cell membrane) Antibodies
Nucleic Acids Formed by chains of nucleotides
Two types : DNA (deoxyribonucleic acid)
Double strand of nucleotides Stores hereditary information
RNA (ribonucleic acid) Single strand of nucleotides Plays a key role in making proteins
Nucleotide
Another important biological moleculeATP (adenosine triphosphate)
– Consists of a single nucleotide with 2 extra phosphate groups.
– ATP stores energy temporarily.– All cells require ATP to function.
2.4 Chemical Reactions Chemistry allows life to function!
Everything living things do is possible due to chemical reactions
The chemistry of breathing
Chemical reactions release or absorb energy.
Activation energy is the amount of energy that needs to be put in to start a chemical reaction.
Exothermic reactions release more energy than they absorb.– Excess energy is released by the reaction
as heat.
Endothermic reactions absorb more energy than they release.– Energy is absorbed by the reaction.
Enzymes– Proteins that increases the speed of a
chemical reactions in cells– Act as a catalyst (reduces the activation
energy needed in a reaction)
Any factor that changes the shape of an enzyme can affect the enzyme’s activity.– An enzyme’s function depends on its
structure.– Denaturing (changing the structure) the
protein by changes in temperature or pH– Example: pepsin
top related