Chapter 2 Need to Know List!!
Atoms: basic unit of matter
Electrons are in cloud around nucleus. Involved in forming bonds so involved in
energy.
Protons: positively charged particle in nucleus (mass number)
Neutrons: neutrally charged particle in nucleus
Mass number: number of protons & neutrons in the nucleus
Atomic number: number of protons in the nucleus
Isotope: same # of protons, diff # of neutrons
Bonds:
covalent: sharing electrons
ex: the O & H of a water molecule
Ionic: bond in which one or more electrons from one atom are removed and
attached to another atom, resulting in positive and negative ions which attract each other.
Ex: NaCL Na loses an electron becomes Na+, Cl gains an electron becoming ClPeptide: covalent chemical bond formed between two amino acids when the
carboxyl group of one molecule reacts with the amino group of the other molecule C, O,
NH
Hydrogen: positive and negative regions are attracted to the oppositely-charged
regions of nearby molecules. hydrogen bonding is not nearly as strong as normal covalent
bonds.
Ex: water molecule to another water molecule
•The attraction created by hydrogen bonds keeps water liquid over a wider
range of temperature than is found for any other molecule its size.
•The energy required to break multiple hydrogen bonds causes water to have a high heat
of vaporization; that is; a large amount of energy is needed to convert liquid water, where
the molecules are attracted through their hydrogen bonds, to water vapor, where they are
not.
Important properties of water:
H2O: Made up of 1 atom of O & 2 atoms of H
Polarity: uneven distribution of electrons between H & O
Expands when frozen
Most abundant compound in living things
Great solvent
Adhesion- attraction of water molecules to other elements
Cohesion- attraction of water molecules to other water molecules
Adhesion & cohesion is due to polarity of the water molecule
High specific heat
Mixtures: Mixture: two or more different substances which are mixed but are not
combined chemically. Each ingredient substance retains its own chemical properties and
makeup.
Solutions:
Solute the substance that is dissolved
Solvent- the reagent in which the substance is dissolved
Solution- molecules are dispersed uniformly throughout the solvent
Suspension- materials never settle to bottom of container
Compound: chemical substance consisting of two or more different chemically bonded
chemical elements, with a fixed ratio.
pH scale:
acids: release hydrogen ions H+, most chemically reactive ion, numbers 1-6 on
pH scale
bases: release hydroxide ions OH- , numbers 7-14 on pH scale
the closer to 7 the weaker the acid or base
mix a strong acid & strong base- neutral solution
neutral-7
buffer: compound that prevents drastic changes in pH
Carbon compounds: contain 4 valence electrons, can polymerize because C can bound
to C to form long chains & rings
Carbon can form very strong covalent bonds because it has 4 electrons in its outer shell
ie. 4 covalent bonds
Isotope: Atoms of the same element can have different numbers of neutrons; the different
possible versions of each element
Inorganic compounds: do not contain carbon, except CO2 belongs in this group
Organic compounds: contain carbon, exception CO2 does not belong
4 groups of macromolecules (organic compounds) found in living organisms:
carbohydrates
lipids
proteins
nucleic acids
Monomer: one unit
Polymer: many monomers bonded through dehydration synthesis to create a complex
macromolecule.
Dehydration Synthesis: used to build polymers from monomers, lose H2O
Hydolysis: used to separate a monomer from a polymer use H20
Carbohydrates: C6H12O6 ratio- 1:2:1
Simplest are monosaccharides or single sugars
A dissacharride (2 single sugars) is formed by dehydration synthesis (loss of
water)
Polysaccharide- many monosaccharides put together, how living things store
excess sugar
Ex: glycogen for animals, cellulose & starch for plants
Polymerization: forms complex carbohydrate molecules by joining
monomers
Isomer: same molecular formula but different arrangement or structural formul
Lipids: composed of a fatty acid & glycerol
waxy, oily organic compounds
Store energy
Form biological membranes
Chemical messengers
Saturated-every carbon atom joined to another carbon atom by a single bond
Unsaturated- a carbon atom joined to another carbon atom by a double bond
Lipids produce more energy than carbohydrates do
Sterol- a type of lipid
Most common is cholesterol
Important in building cells & carrying messages
Phospholipids-a type of lipid
One part dissolves in water the other part doesn’t
Important in forming cell membranes
Proteins: organic compounds
Contain nitrogen, carbon, oxygen, hydrogen
Polymers of amino acids
An amino acid has an amino group at one end (NH2) & a carboxyl(COOH) group
at the other
The amino acids form peptide bond with each other & form long chains
Levels of organization: primary = sequence of AA’s
Secondary= folding or coiling of the chain
1. Enzymes:
Important in: regulating pathways
Transferring information
Lowering the start up energy of a reaction/ releasing energy
Most enzymes are proteins
Enzymes are specific for temp, pH, reaction
Substrates bind to enzymes at its active site- must fit shape of enzyme
Nucleic Acids:
Contain carbon, hydrogen, nitrogen & phosphorus
DNA-deoxyribonucleic acid
RNA-ribonucleic acid
Contain genetic information
Reactions:
Chemical reaction: bonds are broken & forms. Either absorb energy or release
energy. The atoms are rearranged.
Reactants: elements or compounds entering into the reaction
Products: elements or compounds produced by a chemical reaction
Activation energy: energy needed to get a reaction started
Energy absorbing reaction needs more than energy releasing
Catalyst: substance that speed up a reaction (lowers activation energy)
Enzyme: proteins that act as biological catalyst in cells
Regulated by: pH, temp (may denature)
Substrate: reactants of enzyme-catalyzed reaction