Chemistry Chapter 3: Nature and Composition of Matter

Study Notes

Physical properties are characteristics that can be observed and measured without changing the substance's identity. Examples include color, odor, shape, texture, boiling point, and freezing point.
Chemical properties describe a substance's ability to change into a different substance through a chemical reaction. Examples include flammability, acidity, and reactivity with other substances.
Phases of matter describe the different states in which matter exists. The four primary phases are solid, liquid, gas, and plasma.
- Solids have a definite shape and volume.
- Liquids have a definite volume but not a definite shape.
- Gases have neither a definite shape nor a definite volume.
- Plasma is an ionized gas.
Changes of state are physical changes.

Atoms are the basic units of matter.
The nucleus is the center of an atom, containing protons and neutrons.
Protons have a positive charge, neutrons have no charge, and electrons have a negative charge.
- Protons and neutrons make up the mass of the atom, while electrons are so small they contribute very little to the mass.
- Electrons orbit the atom's nucleus.

Atomic number is the number of protons in the atomic nucleus and identifies an atom.
An atom is neutral if the number of electrons equals the number of protons; if not (electrons gained or lost) it will be an ion (cation(+) or anion(-)).
Mass number is the total number of protons and neutrons in an atom's nucleus.
Elements are substances that are entirely composed of one type of atom.
Compounds are formed by the bonding of two or more different types of elements in a fixed ratio, represented by a chemical formula.
- Chemical compounds are formed by chemical actions when atoms combine.

Chemical bonding is the process when combining atoms of elements.
Chemical bonding occurs because of valence electrons.
Atoms combine to form compounds according to rules involving valence electrons.
- Ionic bonding is the transfer of electrons between a metal and nonmetal (metal loses electrons, nonmetal gains electrons).
- Covalent bonding is the sharing of electrons between nonmetals.

Water is a unique substance, essential for life on Earth, with special physical and chemical properties.
- It expands slightly when it transitions from liquid to solid, making ice less dense than liquid water.
A mixture is a substance composed of two or more components not chemically combined.
- Solutions are homogenous mixtures where one substance dissolves in another.
- Suspensions are heterogeneous mixtures with undissolved particles.

Acids are compounds that release hydrogen ions (H+) into a solution. Examples include hydrochloric acid (HCl) and lemon juice.
Bases are compounds that release hydroxide ions (OH−) into a solution. Examples include sodium hydroxide (NaOH) and household cleaners.
Neutralization is a reaction where acids and bases react to form water and a salt.
pH scale measures the acidity or basicity of a solution.

Carbon, hydrogen, oxygen, and nitrogen (CHON) are the four main elements making up most of the chemical compounds in living things (approx 96%.)
Inorganic compounds do not contain both carbon and hydrogen.
- Examples include water, oxygen, carbon dioxide, salt, and hydrochloric acid (HCl)

Cells are the basic unit of living things; eukaryotic cells have a nucleus and other membrane-bound organelles.
Cell membrane is semipermeable; it regulates what enters and leaves the cell.
Cytoplasm is located between the nucleus and the cell membrane; it holds organelles.
Nucleus controls the cell's activities; it contains DNA.
Organelles are specialized structures within cells that carry out specific functions, such as powerhouses for the cell (mitochondria).
Chloroplasts are specialized organelles that perform photosynthesis converting light energy into chemical energy (glucose.)

Different cells are specialized to do different tasks.
Examples include rods and cones for vision and different cells in various organs.

Levels of organization in living things: Cells → Tissues → Organs → Organ Systems → Organisms

Photosynthesis is the process plants use to convert light energy from the sun into chemical energy (glucose).
Reactants are CO2 and H2O; products are Oxygen and glucose.
Critical elements used in this process are Chlorophyll and Pigments.
Photosynthesis takes place in Chloroplasts.

Cellular respiration is the process of converting chemical energy (glucose) into usable energy (ATP).
There are two types of respiration: aerobic, which needs oxygen, and anaerobic, which does not need oxygen.
Aerobic respiration produces many more ATP than anaerobic respiration.
Two main stages, Krebs Cycle and Electron Transport Chain.