Chemistry of LifeHonors Biology: Chapter 2
Matter Everything in the universe is made up
of matter.› Matter- anything occupying space and
has mass. Mass- amount of matter an object has. Weight- force of gravity on a given mass.
Q: Would your weight or mass change if you went to the moon?
Elements and Atoms Elements- pure substances that
cannot be broken down chemically into simpler kinds of matter. › 100+ elements have been discovered.› Less than 30 are important to living things.› Over 90% of the mass of living things
consists of: Carbon (C) Hydrogen (H) Oxygen (O) Nitrogen (N)
Elements and Atoms Periodic Table of Elements- lists
information about each element including the element’s› Chemical symbol- 1-3 letters› Atomic number› Atomic mass
Elements and Atoms Atom- simplest particle of an element
that retains all of the properties of that element.
Nucleus
Elements and Atoms 3 Subatomic Particles in Atoms
› Proton- Positively charged particle found in the atom’s nucleus. ATOMS OF AN ELEMENT ALWAYS HAVE THE SAME NUMBER OF PROTONS.
› Neutron- Found within the nucleus and has no charge.
› Electron- Small negatively charged particles with very little mass. Move in orbitals found outside of the
nucleus.
Elements and Atoms Nucleus
› Most of the atom’s mass› Contains protons and neutrons
Atomic Number = # of protons Mass Number = # of protons + # of
neutrons
Q: How can you determine the number of neutrons an atom has?
A: Mass number – Atomic number = # of neutrons
Elements and Atoms Atoms have a net charge of ZERO.
› # of Protons (+) = # of electrons (-)
Orbital- 3D region around the nucleus indicating the probable location of an electron.› Combination of all orbitals electron cloud› Farther from nucleus greater electron’s energy
Elements and Atoms Orbitals and energy levels:
› Each energy level corresponds to certain orbitals that can hold a set number of electrons. First energy level has 1 orbital- holds
maximum of 2 Second energy level has 4 orbitals that hold
2 electrons each (total of 8).
Elements and Atoms Isotopes- Atoms of the same element
that have a different number of neutrons (number of protons DOES NOT change).› Changes atomic mass
Compounds http://gtm-media.discoveryeducation.c
om/videos/Discovering the Elements/sec2941_300k.asf
Compounds Atoms of most elements readily
combine with the same/different atoms or elements to make compounds.
Compound- atoms of 2+ elements in fixed proportions. › Ex: Water (H2O)
Compounds Chemical and physical properties differ
between compounds and the elements making them up.
Number and arrangement of e- determines how elements combine and form compounds. › Atoms are stable/less reactive when
highest energy level is full. Ex: Noble gases
Chemical Bonds Attractive forces holding atoms
together.› Covalent Bond› Ionic Bond› Hydrogen bond
Covalent Bond Formed when 2 atoms SHARE 1+ pairs
of valence electrons.
Ionic Bonds Transfer of e- from a metal atom to a
nonmetal atom. › More stability for the atoms involved.› Creates ions (charged atoms that have
gained/lost e-)
??Element or Compound??1. HCl2. CO2
3. Cl4. Li5. H2O
HCl, CO2, and H2O- compoundsCl and Li- elements
Energy
Energy and Matter Energy- the ability to do work. Forms of energy include:
› Radiant (light) energy› Thermal (heat) energy› Chemical energy› Electrical energy› Mechanical energy
States of Matter All atoms and molecules in a substance
are in constant motion. Motion of and spacing between
atoms/molecules determine the substances state:› Solid› Liquid› Gas
Solids Move less rapidly than liquids or gases Fixed volume Molecules/atoms more closely linked
than liquids or gases (with the exception of H2O).
Liquid Maintain a fixed volume, but particles
move more freely ability to flow and conform to container’s shape.
Gas Particles move rapidly Little to no attraction to each other. Fill the volume of the container they
occupy.
Energy and Chemical Reactions
Chemical Reaction- change from one substance to another.› Energy is absorbed/released when bonds
are broken and new bonds are formed.
› Ex: CO2 + H2O H2CO3 (see pg 36 Fig 2-6)
Q: Where are the reactants? Products?Q: What does the arrow represent?
Energy and Chemical Reactions
Reactants Products Products Reactants Number of each type of atom must be
EQUAL on both sides of the equation. Reversible reactions shown using
arrows pointing in both directions.
Where Do You Get Your Energy??
Sugars, proteins, and fats in your food get broken down into CO2, H2O, and other products.› Breaking bonds release of energy to be
used in building & maintaining cells, tissues, and organs.
Starting Reactions Activation energy- amount of energy
needed to start a reaction. › Usually a large amount of energy is
needed to start reactions.
Catalysts- reduce the activation energy needed for a reaction without being changed/destroyed. › Enzymes- “special” proteins› RNA molecules
Oxidation-Reduction Reactions Oxidation-reduction reaction = redox
› Oxidation reaction: reactant loses 1+ electrons more + charge
› Reduction reaction: reactant gains 1+ electrons more – charge
› Oxidation reactions are always followed by a reduction reaction.
Redox Reactions Forming Na+ Cl- involves oxidation and
reduction reactions. › Na donates an e- to Cl oxidation of Na to
form Na+› Cl accepts an e- reduction of Cl to form
Cl-
Enzymes Type of protein. Most enzyme reactions are reversible
(arrow goes both ways). Maintain homeostasis: reactions would
not occur fast enough without them. “–ase” = enzyme ONLY react with specific substrates.
THE END!