AP Bio Unit 1: Chapter 2-3

Macroelements

Elements needed in large amounts (ex. important roles: CHONPSK Ca Fe Mg Na Cl)

Microelements

Elements needed in very small quantities (ex. Cu, Co, Zn, Mo, I, Mn)

Chemical bonds

forced that join atoms of elements together. Consist of 4 different types of bonds.

Covalent Bonds

Form when atoms of elements share electrons. There are two types: polar and non-polar.

Polar Covalent

Bond that forms when atoms of elements unequally share electrons, resulting in an electronegative molecule or polar (hydrophilic). Ex. water, H to O bonds (0.5-1.7)

Non-Polar Covalent

Bond that forms when atoms of elements equally share electrons, resulting in neutral molecules (hydrophobic). Ex. carbon to hydrogen. very strong. Have a solid line. Could have single, double, or triple bonds) (0.0-0.5)

Ionic Bonds

Form when electrons are transferred from one atom to another, forming ions. two types of Ions. formed when cations and anions attract each other. have weak chemical bonds. (greater than 1.7)

Cations

have lost electrons, giving them a positive charge

Anions

have gained electrons, giving them a negative charge

Hydrogen Bonds

Weak forced between a positively charged hydrogen atom of one molecule and a negative charged atom of another molecule. Ex. H20→H20 (pos hydrogen atom is attracted to neg oxygen atom). Very weak individual bons

Van Der Waals Forces

Form when electrons shift and form temporary polar surfaces. Ex. lizards climbing

Atomic number

The number of protons in the nucleus.

Atomic mass

The number of protons and neutrons in the nucleus.

Isotopes

Atoms of the same element with different atomic mass. caused by changes in the number of neutrons. Radioactive and Heavy are the types of isotopes

Potential Energy

Energy that matter stores because of its position or location. electrons have potential energy because of their position relative to the nucleus

Electron energy levels/ orbitals

1st level: can have 2 electrons and has the lowest potential energy

Other levels: hold up to 8 electrons and have higher energy levels

Valence electrons

the electrons in the outermost energy level

Molecular Shape

Determines how most molecules of like recognize and respond to one another

Cohesion

water molecules attracting to other water molecules caused by hydrogen bonding. Ex. bodies of water that provide habitat

Surface Tension

Waters inability to bend or stretch. Is the result of cohesion and hydrogen bonding. Ex. Water striders

Adhesion

Water molecules attracting to other substances via hydrogen bonds. Ex. water sticking to vessels

Capillary Action

Waters ability to travel up small tubes despite grativy. caused by cohesion, adhesion, and hydrogen bonding

High Specific Heat

the amount of heat needed to raise 1 g of the sybstance 1 degree Celsius. Hydrogen bonds are strong enough to resist heat changes.

Celsius Scale

used for temp. measurements

Freeze: 0 degrees C

Boil: 100 degrees C

Human body: 37 degrees C

Room temp.: 22-24 degrees C

Water Stabilizes Temperature

Water can absorb and store a huge amount of heat. result climate moderation and organisms are able to survive temperature changes (from the sun)

High heat of vaporization

The quantity of heat a liquid must absorb for 1g of it to convert to a gaseous state. result →evaporative cooling (water cooling organisms from excessive heat build up due to hydrogen bonds)

Water expands when it freezes

The distance between water molecules increased (water has expanded) from the liquid to the solid form due to hydrogen bonding. aquatic life can live under ice layer.

Water is a versatile solvent

Water will form a solution with many materials due to hydrogen bonding

Solution

homogenous mixture of solute and solvent

solvent

liquid doing the dissolving. Ex. water

Solute

substances being dissolved. Ex. NaCl

hydrophilic

Materials that dissolve in water.

Hydrophobic

Materials that repel water.

Solution Concentration

usually based in molarity: number of moles of solute per liter of solution

Moles

molecular weight of a substance in grams; calculation # of atoms x atomic mass = molecular weight

Dissociation of Water

Water can sometimes split into two ions. Adding certain solutes disrupts the balance between the two ions. The two ions are very reactive and can drastically affect a cell.

Acids

Release hydrogen ions when they dissociate “H+ donors” so when things begin with an H they are most likely acidic. Ex. HCl

Bases

release hydroxide ions when they dissociate; if element had OH means it is a bas. Ex. NaOH

Neutrals

Materials that are neither acids nor bases

Buffers

resist pH sifts and maintain a balance; have both acid and base properties

Electronegativity Difference value

subtract larger - smaller electronegativity value