Chemistry of Life (Ch. 2)

What is matter?

Anything with mass and takes up space

What is an element?

A pure substance that cannot be broken down by chemical means

What is an atom?

The smallest unit of an element that retains its properties

What are the 3 subatomic particles?

Protons (+), Neutrons (0), Electrons (-)

What determines the atomic number?

The number of protons

What is atomic mass?

The total number of protons + neutrons

What are isotopes?

Same element, different numbers of neutrons

What is a radioactive isotope?

An unstable isotope that decays over time

What is a molecule?

Two or more atoms bonded together

What is a compound?

A molecule made of at least two different elements

What does a molecular formula show?

The number of each type of atom in a molecule

How many electrons fit in the first shell?

2

How many electrons fit in the second shell?

8

When is an atom stable?

When its outer shell is full

What is a covalent bond?

Atoms share electrons

Difference between nonpolar and polar covalent bonds?

Nonpolar = equal sharing; Polar = unequal sharing

What is a hydrogen bond?

Weak attraction between polar molecules (ex: water, DNA)

What is an ionic bond?

Electrons are transferred, forming oppositely charged ions.

What is cohesion?

Water molecules sticking to each other

What is adhesion?

Water molecules sticking to other surfaces

What is surface tension?

Water resisting breaking at the surface

Why does ice float?

It's less dense than liquid water

Why is water a good solvent?

Its polarity dissolves polar and ionic substances

How does water regulate temperature?

It absorbs and releases heat slowly

What is an acid?

A substance that adds H⁺ ions (pH < 7)

What is a buffer?

A substance that keeps pH stable

What is the monomer of carbohydrates?

Monosaccharides (sugars).

Examples of carbohydrates?

Glucose, starch, glycogen, cellulose

What is the monomer of proteins?

Amino acids (20 types)

What bond links amino acids?

Peptide bond

What determines protein function?

Its shape (structure)

What can denature proteins?

Heat, pH, or salt

What is the monomer of nucleic acids?

Nucleotides (sugar + phosphate + nitrogen base)

What are the nitrogen bases in DNA?

A-T, G-C

What are the nitrogen bases in RNA?

A-U, G-C

What is DNA's role?

Stores recipes (genes) for proteins

What are lipids made of?

Mostly C, H, O (hydrophobic, no true monomer)

What are examples of lipids?

Fats, phospholipids, steroids

Difference between saturated and unsaturated fats?

Saturated = straight chains, solid (animal fats)

Unsaturated = bent chains, liquid (plant fats)