PART2 - CHEMISTRY OF LIFE

4 Major Elements in Living Things

Carbon, hydrogen, oxygen, nitrogen​

Atom and Subatomic Particles:

Atom: Smallest unit of an element.

Protons: Positive charge; define atomic number.

Neutrons: No charge; contribute to atomic mass.

Electrons: Negative charge; involved in bonding.

Define atomic number and atomic mass.

Atomic Number: Number of protons.

Atomic Mass: Protons + neutrons.

How to find protons, neutrons, electrons?

Protons = atomic number;

neutrons = atomic mass - atomic number;

electrons = protons in neutral atoms

Valence electrons? How to determine them?

Valence Electrons: Outer shell electrons for bonding.

Determine: Based on group number on the periodic table.

Covalent bond? Nonpolar vs. polar covalent?

Covalent Bond: Shared electrons.

Nonpolar: Equal sharing (e.g., O₂).

Polar: Unequal sharing (e.g., H₂O).

ionic bond form? example

Ionic Bond: Transfer of electrons; e.g., NaCl.

cation and anion?

Cation: positive ion
Anion: negative ion

Bonds in and between water molecules?

Within: Covalent bond.
Between: Hydrogen bond

Unique properties of water?

Cohesion: Sticks to itself.

Adhesion: Sticks to other surfaces.

High Heat Capacity: Absorbs heat slowly.

Solvent: Dissolves substances.

Difference between acids and bases? Examples

Acid: Donates H+ (e.g., HCl).
Base: Accepts H+ (e.g., NaOH)

What is pH? Acid, base range on pH scale?

pH Scale: Measures acidity.
Acids: 0-6.
Neutral: 7.
Bases: 8-14.

How much stronger is pH 2 compared to pH 5?

pH 2 is 1,000 times more acidic than pH 5