Log Dog
1. Structure of Matter
● Matter: Anything that has mass and takes up space. All matter is made up of atoms.
● Atom: The smallest unit of matter that retains the properties of an element.
● Subatomic Particles:
○ Protons (p+): Positively charged; found in the nucleus.
○ Neutrons (n0): No charge; found in the nucleus.
○ Electrons (e−): Negatively charged; found in the electron cloud surrounding the
nucleus.
● Nucleus: Dense center of an atom containing protons and neutrons.
Know this:
✔ Protons and neutrons are inside the nucleus.
✔ Electrons occupy the space outside the nucleus.
✔ Number of protons = atomic number (identifies the element).
2. Atomic Number and Atomic Mass
● Atomic Number: Number of protons in an atom.
○ Example: If an atom has 15 protons, its atomic number is 15.
● Atomic Mass (Mass Number): Protons + Neutrons.
○ Example: Phosphorus (P) has an atomic number of 15 and a mass number of 31.
■ Protons = 15
■ Neutrons = 31 - 15 = 16
■ Electrons = 15 (in a neutral atom)
● Isotopes: Atoms of the same element with the same number of protons but different
numbers of neutrons.
Know this:
✔ Electrons are much smaller than protons and neutrons.
✔ In a neutral atom: Protons = Electrons.
3. Electron Arrangement
● Electrons are arranged in energy levels (shells):
● Valence Electrons: Electrons in the outermost shell.
Know this:
✔ Atoms form bonds to achieve stability by filling their outer shells.
✔ Hydrogen has 1 proton and 1 electron; it needs 1 more electron to be stable.
4. Chemical Bonds
● Chemical Bond: Attraction between atoms that allows them to form compounds.
● Types of Bonds:
○ Ionic Bonds: Transfer of electrons from one atom to another.
○ Ions:
■ Example: Sodium (Na+) + Chlorine (Cl−) = NaCl (table salt).
○ Covalent Bonds: Sharing of electrons between atoms.
■ Single bond: Shares 1 pair of electrons (2 total).
■ Double bond: Shares 2 pairs of electrons (4 total).
■ Triple Bond: Shares 3 pairs of electrons (6 total).
○ Hydrogen Bonds: Weak attractions between polar molecules (important in water
and DNA). (Only N, O, or S)
Know this:
✔ Ionic bonds = electron transfer; Covalent bonds = electron sharing.
✔ Hydrogen bonds are weaker than ionic or covalent bonds.
5. Molecules and Compounds
● Molecule: Two or more atoms held together by covalent bonds.
● Compound: A substance made of two or more different elements chemically combined.
● Chemical Formula: Shows the number and type of atoms (e.g., H2O, CO2).
6. Water and Its Importance
● Water is a polar molecule:
○ Oxygen is slightly negative; hydrogen is slightly positive. This is due to the size of
oxygen trapping most of the electrons on its side.
● Water (due to hydrogen bonding) can do some special things:
○ Cohesion: Water molecules stick to each other.
○ Adhesion: Water sticks to other substances.
○ High specific heat: Resists temperature changes.
○ Expands when frozen: Ice is less dense than liquid water.
● Why does sugar dissolve in water but oil does not?
○ Water dissolves polar and ionic substances but not nonpolar substances like
oil.
7. Things to Know for the Test
● All matter is made of atoms.
● The three subatomic particles and their charges:
○ Proton = positive, neutron = neutral, electron = negative.
● Location of particles: protons/neutrons in the nucleus; electrons in electron cloud.
● Difference between atomic number and atomic mass.
● What makes an atom neutral vs. an ion.
● Why atoms form bonds (to fill outer shell and become stable).
● Difference between ionic and covalent bonds.
● How hydrogen bonding makes water unique.
● How to calculate number of protons, neutrons, and electrons from atomic number
and mass.
● Electron shell arrangement and valence electrons.
● Be able to identify the type of bond in an example (ionic, covalent, hydrogen).
● Hydrogen Bonding only occurs with N, O, or S as the elements.
● Examples of compounds (NaCl, H2O, CO2).
● What makes water polar and why polarity matters.
● How can I balance a chemical equation with the numbers
● Phospholipids are hydrophilic and help form the cell membrane
8. What Are Macromolecules?
● Definition: Large molecules necessary for life, made up of smaller units called
monomers.
● Importance: All living things depend on these molecules for energy, structure, and
cellular function.
● The Four Main Types:
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic Acids
1. Carbohydrates
● Function: Primary source of quick energy for cells; provides structural support in plants.
● Monomer: Monosaccharides (simple sugars like glucose, fructose, galactose)
● Polymer: Polysaccharides (starch, cellulose, glycogen)
● Examples & Roles:
○ Glucose: Main energy molecule for cells.
○ Starch: Energy storage in plants.
○ Glycogen: Energy storage in animals.
○ Cellulose: Structural support in plant cell walls.
● Key Fact: Usually made of carbon, hydrogen, and oxygen in a 1:2:1 ratio.
2. Lipids
● Function:
○ Long-term energy storage.
○ Forms cell membranes (phospholipids).
○ Acts as chemical messengers (hormones like steroids).
● Structure: Made mostly of carbon and hydrogen atoms; generally nonpolar (do not
mix with water).
● Monomers: Glycerol + Fatty Acids.
● Examples:
○ Fats & Oils: Energy storage.
○ Phospholipids: Make up cell membranes.
○ Steroids: Hormones like testosterone and estrogen.
3. Proteins
4. Nucleic Acids
● Structure: Made of nucleotide monomers, each containing:
○ A sugar,
○ A phosphate group,
○ A nitrogen base.
● Function: Stores and transmits genetic information in the form of a code.
● Types:
○ DNA (Deoxyribonucleic Acid): Stores genetic information.
○ RNA (Ribonucleic Acid): Helps build proteins from genetic code.
● Key Fact: DNA and RNA have different sugars in their nucleotides.
Summary
● All living organisms depend on macromolecules for survival.
● The four macromolecules are polymers made from simple units called monomers.
● Each type has a different structure, function, and role in living things:
○ Carbohydrates: Quick energy and structural support.
○ Lipids: Long-term energy, membranes, signaling.
○ Proteins: Structure, enzymes, transport.
○ Nucleic Acids: Genetic information storage and transfer.