Science Class Notes: Chemistry, Physics & Biology
Lesson 1: Atoms, Elements, Properties & Changes
Atoms & Elements
Atom: The smallest unit of matter. Example: Oxygen atom (O)
Element: A pure substance made up of only one type of atom. Example: Carbon (C)
Properties of Matter
Physical properties: Characteristics observed without changing the substance. Example: Color, density, melting point.
Chemical properties: Characteristics that describe how a substance reacts with others. Example: Reactivity, flammability.
Changes in Matter
Physical change: Does not result in a new substance. Example: Melting (physical change).
Chemical change: Results in a new substance. Example: Burning (chemical change).
Lesson 2: Properties & Changes, and The Elements
Physical & Chemical Changes
Physical change: Change in appearance without forming a new substance. Example: Ice melting into water.
Chemical change: New substance(s) formed with different properties. Example: Burning paper turns it into ash and smoke.
Elements
Elements: Substances made up of one type of atom. Example: Oxygen (O), Carbon (C), Hydrogen (H).
Lesson 3: The Elements & Periodic Table
Groups in the Periodic Table
Elements are organized into groups based on similar properties and electron configuration.
Example: Group 1 elements (alkali metals) like Sodium (Na) have one valence electron and are highly reactive.
Atomic Number & Mass
Atomic number: The number of protons in an atom’s nucleus. Example: Carbon (C) has an atomic number of 6.
Atomic mass: The sum of protons and neutrons in an atom’s nucleus. Example: Carbon with 6 protons and 6 neutrons has an atomic mass of 12.
Lesson 4: Models of Atomic Structures
Atomic Models
Atomic model: Representation of an atom’s structure. Example: Bohr model shows electrons in energy levels around the nucleus.
Subatomic Particles
Subatomic particles: Protons (+), neutrons (0), and electrons (-) make up an atom.
Example: Protons determine the element’s identity.
Lesson 5/6: Chemical Bonding
Chemical Bonds
Chemical bond: Force that holds atoms together in compounds. Example: Sodium (Na) and Chlorine (Cl) bond to form Sodium Chloride (NaCl).
Types of Bonds
Ionic bond: Transfer of electrons between atoms. Example: Sodium donates an electron to Chlorine to form NaCl.
Covalent bond: Sharing of electrons between atoms. Example: Oxygen (O) shares electrons with another Oxygen atom to form O2 (oxygen gas).
Molecules
Molecule: Group of atoms held together by chemical bonds. Example: H2O (water) is a molecule made of two Hydrogen atoms and one Oxygen atom.
Lesson 7: Static Electricity
Static Electricity & Charges
Static electricity: Build-up of electric charges on an object. Example: Rubbing a balloon on hair creates static electricity.
Positive and negative charges: Opposite charges attract, while like charges repel.
Lesson 8: Electricity on the Move
Current Electricity & Circuits
Current electricity: Flow of electric charges through a conductor. Example: Electric current in a wire powers electrical devices.
Circuit: Path for electricity to flow. Example: Simple circuit includes a battery, wires, and a light bulb.
Lesson 9: Electricity & Practical Applications
Voltage & Resistance
Voltage: Electric potential difference that pushes electric charges. Example: Battery provides voltage to create a flow of electrons.
Resistance: Opposition to the flow of electric current. Example: Thin wires have more resistance than thick wires.
GRASP Method for Word Problems
- Given: What do you know?
- Required: What do you want to know?
- Analysis: What formula can you use?
- Solution: Show your work.
- Paraphrase: State the answer in a sentence.
Useful Formulas
Density: Density = Mass / Volume
Speed: Speed = Distance / Time
Acceleration: Acceleration = (Final Velocity – Initial Velocity) / Time
Plant & Animal Cells
- Nucleus: Controls cell activities and contains genetic material.
- Mitochondria: Produces energy through cellular respiration.
- Cell Membrane: Controls the movement of substances in and out of the cell.
- Chloroplasts (plants only): Site of photosynthesis, contains chlorophyll.
Photosynthesis
Process: Chlorophyll captures light energy to convert it into chemical energy (glucose).
Reactants: Carbon dioxide (CO2) and water (H2O).
Products: Glucose (C6H12O6) and oxygen (O2).
Cellular Respiration
Process: Converts glucose and oxygen into energy, carbon dioxide, and water.
Reactants: Glucose (C6H12O6) and oxygen (O2).
Products: Carbon dioxide (CO2), water (H2O), and ATP (energy).
Ecosystems
Components of an Ecosystem
Producers: Convert sunlight into energy through photosynthesis.
Consumers: Obtain energy by consuming other organisms.
Decomposers: Break down dead organisms and recycle nutrients.
Ecosystem Dynamics
Food Chains: Sequence of who eats whom in an ecosystem.
Food Webs: Interconnected food chains in an ecosystem.
Energy Flow: Transfer of energy through trophic levels.