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CHEMISTRY
Composition of Matter
Energy
Solutions
Composition of Matter
Why discuss chemistry in biology class?The structure and function of all living things
are governed by the laws of chemistry
Matter
Makes up everything in the universe Anything that occupies space and has
massMass is not = to weight
○ Weight is the pull of gravity on an object (mass would not change because it is the “quantity of matter” an object has…
○ You would still be the same “being” on Earth and on the moon = your mass doesn’t change…HOWEVER…your weight would be significantly less on the moon due to the pull of gravity
Chemical changes in matter
Essential to all life processes Living things are made up of the same
kinds of matter that make up nonliving things
Understanding changes in matter = understanding of life processes of organisms
Elements
Pure substances that cannot be broken down chemically into simpler kinds of matter90% of mass of all kinds of living things is
composed of combinations of 4 elements:○ Oxygen (O)○ Carbon (C) ○ Hydrogen (H)○ Nitrogen (N)
Chemical Symbols
Atomic Number
Chemical Symbol
Atomic Mass
Name
Atoms Simplest particle of an element
that retains all of the properties of that elementNucleus = core of atom
○ Made of protons (+) and Neutrons (no charge)All atoms of a given element have same
# of protonsAtomic # = number of protons
Electrons ○ High energy particles; negatively
charged; move about nucleus at very high speeds in “energy levels”
○ First e- level = up to 2 e-○ Second e- level = up to 8 e-
AtomicEnergyLevels
Compounds
Under natural conditions, most elements do not exist by themselves
A compound is a pure substance that is made up of atoms of two or more elements that are fixed = water: H2O = chemical formula indicates that the atoms always combine in a proportion of two Hydrogen atoms to one Oxygen atom
Making Compounds
Stable atom = outermost energy level is filled
Most atoms are not stable in natural state = meaning they tend to react/combine with other atoms in order to achieve stability
Undergo chemical rxns to achieve stability = chemical bonds are broken; atoms are rearranged; new bonds are made
Bonds
Covalent = 2 atoms share one or more pairs of e-
Ionic= one e- gets transferred from one atom to another, resulting in more stability and giving both atoms a charge of + or -
You payin’ attention????
What are you to do now? You are going to complete a “Guided
Notes” (GN) activity…
On page 35 of your textbook, you will notice that there are 4 objectives listed. Make a chart/table using the objectives and take notes from the reading.
Ex: Objective Notes
List the three states of matter, and explain how matter can change state
• Your notes will go here• You can bullet• Leave space so that
you can take notes in class!
Back to our notes!!!!!
Energy - E
Energy is the ability to do work Biological systems need/use: chemical
energy, thermal energy, electrical energy, and mechanical energy
Free energy = energy available for work (cell processes would benefit from this)
Do Right this Very Minute (DRTVM) Two Truths and a Lie….
Take an index card from the front deskFrom the homework (a few nights ago), write
down two truths and a lie about “Energy” You have 2 minutes!When 2 minutes are up…you are to find 3 people
NOT at your table and try to trick them…Write down all 3 names on the other side of your
card and write down if they picked the lie or not…You have 5 minutes!
States of Matter Solid, liquid, or gas
Atoms in constant motion…their speed determines the state…Solid = particles are tightly linked in
definite shape (fixed volume and shape)
Liquid = particles are not as tightly linked (fixed volume)
Gas = particles move most rapidly; move freely; little or no attraction to each other
*Thermal energy must be added to change a state
Energy and Chemical RXNs
Chemical Rxns
Our bodies need a lot of energy…we get it from breaking down sugars from food into CO2 and H2O
Exergonic = chem. rxn where E is released
Endergonic = chem. rxn where E is absorbed
Activation E
What gets you up and moving faster???
Really…activation E the amt of E needed to start a rxn
Catalysts lower the amt of activation E necessary for rxn
Enzymes are important catalysts to living things – specific to individual chemical rxns
E movement
Constant flow of energy into and throughout living things
Many involve transfer of e- between atoms
Redox Reactions – These work together
When a compound becomes “oxidized”it loses its electrons to another compound…
When a compound gains electrons, it becomes negativelycharged, or reduced.
Solutions (solns) Solution (soln) – 1+ substances are =
distributed in another substance Solute – dissolved substance Solvent – does the dissolving (water is the
universal solvent) Concentration – measurement of amt of
solute dissolved in a fixed amt of soln Saturated soln – no more solute can
dissolve Aqueous soln – water is solvent
Dissociation of H2O
Breaking apart of water
Acids and Bases
When an acid is introduced into a neutral solution, it adds H+ ions
When a base is introduced into a neutral solution, it adds OH- ions
pH Scale developed to
compare the relative concentration of hydronium ions and hydroxide ions in a solution
Ranges from 0 to 14 0 = very acidic 14 = very basic 7 = neutral (water)
See Figure 2-10 on page 42
BuffersDefinitely NOT this guy!
Chemical substances that neutralize small amts of either an acid or a base added to a soln