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

Carbon Isotopes

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

Activation Energy

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.

Enzymes

THE END!