Download BIOCHEMISTRY: The Chemistry of Life Chemistry of Life: ATOMS

2/6/2015
BIOCHEMISTRY: The Chemistry of Life
Atoms, Water, Carbon & Macromolecules
Chemistry of Life: ATOMS
• ATOM: smallest particle of matter, neutral • Parts:
– Nucleus (center), Mass of Atom
• Protons (+)
• Neutrons (0)
– Energy Level (Outside nucleus)
• Electrons (‐), no mass
• Valence Electrons: the electrons found in the LAST energy level, can leave the atom
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Chemistry of Life: ATOMS
• Atomic #:
–# of Protons in an atom
–Order on the Periodic Table of Elements
• Atomic Mass:
–Sum of the Protons & Neutrons in the nucleus of the Atom
– Atomic Mass – Atomic # = # of Neutrons
Chemistry of Life: ATOMS
• ELEMENTS are made up of ONE type of ATOM
– Differ by the # of protons (Atomic #)
• Most Common Elements in Organisms: C, H, N, O, P, S
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How is an ION different from an ATOM?
• Atoms have an EQUAL number of protons and electrons
• Ions have an UNEQUAL number of protons and electrons, have a CHARGE
– Cation: more protons than electrons, POSITIVE charge, LOSE electrons
– Anion: more electrons than protons, NEGATIVE charge, GAIN electrons
• WHY can’t an atom gain or lose PROTONS to become an ion???
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Atomic Bonding
• When 2 or more atoms are chemically combined, they form a COMPOUND
• Covalent Bond: a chemical bond in which 2 or more atoms SHARE
valence electrons
• Compounds formed by covalent bonds: MOLECULES
Chemical Reactions
• A process that turns one set of substances into a completely different set of substances
• Chemical composition is changed
• REACTANTS (ingredients) are turned into PRODUCTS (end result)
• Examples:
– Flour, sugar, eggs, milk, baking soda  A cake
– Paper + Flame = ashes
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Chemical Reactions
• Reactants vs. Products
http://www.youtube.com/watch?v=m55kgyApYrY
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Why is Water so SPECIAL?
Water Survey: What do you know?
Polar Structure of Water
• Water is a polar covalent molecule: – Covalent: Hydrogen and Oxygen atoms SHARE electrons
– Polar: The valence electrons are not equally shared
• Oxygen has a stronger hold on the electrons, partially negative, “BULLY”
• Hydrogen atoms have a positive charge
• Water’s polarity makes it good at DISSOLVING other substances!
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Bonds in Water
• Covalent Bond
– Bond between Hydrogen and Oxygen in the SAME
molecule
– holds water molecules together
• Van der Waals Forces: A bond caused by the attraction between positive and negative charges in different
molecules
– Hydrogen Bond
• Weak Van der Waals bond • Occurs between a Hydrogen in one molecule and an Oxygen in a DIFFERENT molecule
• Connects different water molecules together (chain)
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Why is WATER so important?!
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Natural Solvent
3 States of Matter
Habitat & Environment
Metabolism of Organisms
Photosynthesis
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1. The Natural Solvent
Water’s POLARITY makes it good at Dissolving other substances!
• Solution: A solution is a mixture in which one or more substances (solutes) are dissolved evenly in another substance (solvent). • Solute – substance dissolved in a solvent to form a solution • Solvent – fluid that dissolves solutes
• Example: Lemonade– water is the solvent
and powder mix is the solute
What dissolves in Water?
• Salt http://www.youtube.com/watch?v=xdedxfhcpWo
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2. States of Matter
• Water can exist as a SOLID, LIQUID & GAS on Earth
• Water Cycle is necessary for the environment
• Water is LESS dense as a solid
– Ice floats in liquid water
– Protects aquatic life in ponds, lakes, oceans
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3. Habitat & Environment
• Water covers 70% of Earth’s surface
• Habitat for many organisms
• Controls temperature of Earth’s climates
– Absorbs energy with little temperature change: SPECIFIC HEAT
• Carries nutrients to many locations
– Streams & Rivers
4. Metabolism of Organisms
• Metabolism: the collection of all the chemical reactions in your body that keep you alive
• Water makes up 70% of our bodies
• Water is a necessary REACTANT in many chemical processes in our bodies
• Controls temperature in our bodies
– Sweating, 98.6 degrees F
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5. Photosynthesis • Water is one of the necessary REACTANTS in Photosynthesis
– Plants are AUTOTROPHS: make their own food (glucose)
• We cannot survive without healthy plants!
Properties of Water
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cohesion = water attracted to other
water molecules because of polar
properties
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adhesion = water attracted to
different molecules
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surface tension = a measure of the
strength of the COHESION forces
between liquid molecules, how much
“stretch” before the bonds break,
drops on a penny
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Surface Tension
– Water has a greater surface tension than most other liquids because hydrogen bonds among surface water molecules resist stretching or breaking the surface.
– Water behaves as if covered by an invisible film.
– Some animals can stand, walk, or run on water without breaking the surface.
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Basilisk Lizard
• http://www.youtube.com/watch?v=45yabrnry
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Capillary Action
- Combination of both
adhesion and cohesion.
Capillary Action = water moves upward due to its
attraction to other water molecules and the
substance it is moving through
Ex: Water moves through plant stems
Ex: Water flows backwards through hose
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Specific Heat
• Amount of energy required to raise the temperature of a substance 1 degree Celsius. – 1 calorie/gram °C = 4.186 joule/gram °C
• Water has a HIGH specific heat = requires a LOT of energy
– Due to Hydrogen bonds between water molecules (changes states of matter)
– Temperature regulation of Earth & us!
– Think of ocean temperature in the summer.
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THINK!
1) Is water an acid or a base?
2) Do you think blood is an acid or a base? Why?
3) Toothpaste commercials talk about “enamel erosion” of your teeth. Do you think ACIDIC or BASIC solutions “eat away” your tooth enamel? What specific beverages do you think do this?
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Acids and Bases
• pH: measure of the concentration of Hydrogen ions (H+) in a
solution.
• Strength compared using pH scale
• Ranges from 0 (acidic) – 14 (basic)
• Acid: a substance that produces H+ ions when placed in water
• Ranges from pH 0-6.9
• Ex. HCl, Vinegar, Lemon Juice
• Base: a substance that produces -OH (hydroxide) ions when
placed in water
• Ranges from pH 7.1 – 14
• Soaps, Baking Soda, Ammonia
• Distilled water is pH 7.0 or neutral.
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Acids and Bases
Buffers – substance used to maintain a
contant pH within a system
H2CO3
Carbonic acid
H+ + HCO3bicarbonate ion
Acids and Bases
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13.Element
24.Cohesion
Atom
14.Reactant
25.Adhesion
Nucleus
15.Product
26.Surface Proton
tension
16.Cation
Neutron
27.Capillary Energy level 17.Anion
action
Electron
18.Polar
Valence 19.Van der Waals 28.Specific heat
29.Acid
Force
electron
30.Base
20.Hydrogen 8. Atomic #
bond
31.pH
9. Atomic Mass
32.Buffer 10.Covalent bond 21.Solution
22.Solute
11.Molecule
12.Compound 23.Solvent
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