A&P: Ch 2: Chemistry

Matter

anything that has mass and occupies space

Solid

definite shape and volume

liquid

changeable shape; definite volume

gas

changeable shape and volume

Kinetic

energy in action

Potential

stored (inactive) energy

elements

Four elements make up 96% of body:

• Carbon, oxygen, hydrogen, and nitrogen

• 9 elements make up 3.9% of body

• 11 elements make up <0.01%

Covalent Bonds

two atoms that share one or more pairs of electrons

Why they are important: they share pairs of electrons to hold atoms together and create the stable molecules needed for life 

Ionic bond

a strong chemical link formed when one atom gives up one or more electrons to another atom 

Why they are important: creating oppositely charged ions that stick together through electrostatic attraction 

Hydrogen bond

 weak type of attractive interaction that forms when a hydrogen atom covalently bonded to a strongly electronegative atom (like oxygen, nitrogen, or fluorine) experiences an electrostatic attraction to another nearby electronegative atom 

Why are they important: 

Water properties: They give water a high boiling point and make it liquid at room temperature.

Polar covalent bond

Unequal sharing: One atom pulls the shared electrons closer to itself.

Charge distribution: Creates partial charges—a slightly negative charge on the stronger atom and a slightly positive charge on the weaker atom.

Nonpolar convalent bond

 Equal sharing: Atoms share their electrons equally.

Charge distribution: There are no positive or negative poles.

Ex. carbon dioxide

electrolytes and ionic bonds

Electrolytes form when ionic compounds dissolve in water and their ionic bonds break apart into free moving, charged ions 

Carbohydrates

• Building blocks: Simple sugars or monosaccharides (like glucose).

• Main job: Provide fast, easy energy for your cells and brain.

Lipids

• Building blocks: Glycerol and fatty acids.

• Main job: Store long-term energy, protect organs, insulate the body, and build cell membranes

Proteins

• Building blocks: Amino acids.

• Main job: Build and fix tissues (like muscles), speed up chemical reactions as enzymes, and support the immune system.

 phospholipid

a fat-like molecule with a water-loving (hydrophilic) head and two water-fearing tails (hydrophobic)

naturally line up in two rows to make a lipid bilayer.

The inner core stops large or charged items from crossing easily.

Bent or straight tails keep the membrane flexible so the cell can move and change.

host proteins and cholesterol to help the cell communicate and function

Acids

proton donors, they release hydrogen ions (H+), less than 7

bases

more than 7, Substances that accept hydrogen ions or release hydroxide ions (OH⁻) into a liquid. They often taste bitter, feel slippery, and turn red litmus paper blue. Examples include soap and baking soda