BIO CH 2

What is an atom?

basic building block of all physical matter in the universe

What is a molecule?

a group of atoms held together (bonded) by energy in a stable association

Atomic Structure

1. Protons ( + charge) in nucleus

2. Neutrons ( no charge) in nucleus

3. Electrons (- charge) found in orbitals surrounding nucleus

Be able to identify atomic #, symbol, and mass

Atomic Number gives you the what?

Number of protons

Atomic mass gives you the what

amount of matter in an atom

Ions

Charged particles (unbalanced)

Cation: + charge, looses electrons

Anions: - charge, gains electros

change in particle dictates how it behaves in the body

What is an Isotope?

Have same # of protons but different neutrons

Radioactive Isotopes

unstable and emit radiation as the nucleus breaks up (radioactive decay)

Electron Arrangement

Key to the chemical behavior of an atom lies in the number and arrangement of its electrons in their orbitals

Electron energy levels

• Electrons have potential energy related to their position

• Electrons farther from nucleus have more energy

Valence electrons

Outermost orbital

when shell is full (8) atom is stable

Inert elements (nonreative)

have a full valence shell and are stable

Molecules

groups of atoms held together (bonded) in a stable association

Compounds

molecules containing more than one type of element

Ionic Bonds

• Opposites attract

• gain or loss electrons

• Transfer of electorns

Covalent Bonds

Formed when atoms share 2 or more electrons

more electrons share = stronger bond

Hydrogen Covalent

• covalent bond

• no net charge

• octet rule satisfied

Properties of covalent bonded molecules

• Very strong

• requires energy to break

• low boiling points

• Typically, not soluble in water

Non-polar covalent bonds

share electrons equally

Polar covalent bonds

Share electrons unequally

Hydrogen Bond

form when a partially charged atom is attracted to hydrogen ( weak bond)

What is a chemical reaction?

Involves formation or breaking of bonds

Reactants

Original molecules

Products

Molecules resulting from reaction

Water

• ability to from hydrogen bonds (b/c molecule is partially charged)

• bond is strong enough to keep it together but weak enough so its constantly moving

• Water has specific heat

Adhesion and Cohesion in water

Cohesive: water moleculs attract to one another

Adhesion: attract to other polar molecules

What is pH

Used to measue the amount of Hydrogen in a solution

what is an acid

substance that increases hydrogen atoms

What is a base

substance that decreases hydrogen atoms

Whats the blood pH? Why must the body maintain certain pH?

7.35-7.45

To maintain homeostasis

If pH changes what can occur?

proteins can begin to denature (unfold)

What are buffers?

substances that resist changes in pH

goal: to keep Hydrogen atoms constant

biological buffers consist of what?

pair of molecules, on an acid and the other a base.

Carbonic acid buffer system

Helps out bodies transport CO2 and O2 in our bodies

Keeps the blood at a certain pH