Bio Adv: Unit 2 - Atoms and Molecules Study Guide 3

hydrogen bonding

when partial charges on one molecule are attracted to the opposite partial charge on a neighboring molecule; found between H and O, N, F

cohesion

tendency for molecules of the same kind to stick together

surface tension

special resistance to being broken

adhesion

water's tendency to stick to other substances or objects

transpirational pull

trees use cohesion and adhesion to pull water from roots to leaves → water moves through the xylem in trees, illustrating cohesion-tension theory; ex: oak tree can move about 110 g of water daily

specific heat capacity

amount of heat required to raise the temperature

boiling/freezing points

freezes at 0 degrees Celsius and boils at 100 degrees Celsius

density

amount of space molecules take up

solubility

ability to dissolve other polar or ionic substances

acid

any substance that releases H+ ions into the solution when it dissolves

base

any substance that takes H+ ions out of a solution

pH scale

measurement system that indicates the concentration of H+ ions in a solution; ranges from 0-14; pH of 7 indicates a neutral solution

buffer

weak acids or bases that can react with strong acids or bases to prevent sharp sudden changes in pH

What type of bond forms when the partial positive charge of a hydrogen atom is attracted to the partial negative charge of an electronegative atom on a neighboring molecule?

Hydrogen bonding

Which electronegative elements commonly participate in hydrogen bonding with hydrogen in biological molecules?

Oxygen, Nitrogen, and Fluorine (O, N, F)

What property of water refers to the tendency of water molecules to stick to other water molecules?

Cohesion

Why does an overfilled glass of water bulge upward slightly without spilling over immediately?

Cohesion between water molecules

What property describes the special resistance of a liquid surface to being broken?

Surface tension

Which property allows light insects to walk across the surface of a pond without sinking?

Surface tension

What property describes water's tendency to stick to other different substances or objects?

Adhesion

What causes water to creep up the sides of a curved glass tube like a buret?

Adhesion

What process allows trees to pull water upward from their roots to their leaves through xylem vessels?

Transpirational pull (Cohesion-tension theory)

How much water can a typical oak tree transport daily through transpirational pull?

About 110 grams of water

What term is defined as the amount of heat required to raise the temperature of a substance?

Specific heat capacity

Why does water require a large amount of thermal energy to increase in temperature or change phase?

High energy is needed to break the strong hydrogen bonds between water molecules

At what temperatures in Celsius does water freeze and boil?

Freezes at 0°C and boils at 100°C

Why is solid ice less dense than liquid water?

Ice forms a stable hydrogen bonding crystal lattice that holds molecules farther apart, taking up more space

What ecological process occurs when melting ice becomes denser and sinks, circulating nutrients and oxygen in lakes?

Spring overturn

What term describes a fluid that has the ability to dissolve other polar or ionic substances?

Solvent (or Universal Solvent)

What is the term for a substance (solid, liquid, or gas) that gets dissolved in a solvent?

Solute

What type of homogeneous mixture is formed when a solute completely dissolves into a solvent?

Solution

How does water dissolve ionic compounds like table salt (NaCl)?

Polar water molecules attract oppositely charged ions and pull them apart

What is an acid defined as in terms of ion concentration?

A substance that releases H+ ions into a solution when dissolved

What is a base defined as in terms of ion concentration?

A substance that removes or accepts H+ ions from a solution

Which strong acid completely dissociates in the human body to aid in food digestion?

Hydrochloric acid (HCl)

What is the range of the pH scale, and what value represents a neutral solution?

The scale ranges from 0 to 14, and 7 represents a neutral solution

How do the concentrations of H+ and OH- ions compare in a neutral solution like pure water?

The concentration of H+ ions equals the concentration of OH- ions ([H+] = [OH-])

What type of solution has a pH below 7 and a higher concentration of H+ ions than OH- ions?

Acidic solution

What type of solution has a pH above 7 and a lower concentration of H+ ions than OH- ions?

Basic (or alkaline) solution

What is the normal homeostatic pH range of fluids inside most human body cells?

Between 7.35 and 7.45

What chemical compounds prevent sharp, sudden changes in pH by reacting with strong acids or bases?

Buffers