I. Atomic Structure and Periodic Table
A. Atoms are made of subatomic particles called protons, neutron, and electrons. Protons (1 amu) are positive, Neutrons (1 amu) are neutral, and electrons (0 amu) are negative.
B. Elements (made of 1 type of atom) are identified on the Periodic Table and are arranged in order of Atomic Number (the number of protons or electrons). Atomic mass is the number of protons and neutrons in an atom. When elements combine they form compounds (example: H2O)
*Groups are vertical (up and down) and periods are horizontal (across) in the periodic table.
C. Atomic Theory states that all matter is made of atoms, and that different elements are made of different types of atoms. Many scientists have contributed to this theory over time through experimentation.
II. Chemical Properties
A. Chemists observe substances in order to identify their properties (examples include boiling point, melting point, color, texture, smell)
B. Different substances have different properties because they are made of different types and numbers of atoms that repeat.
C. Scientists can use properties to help them distinguish (tell the difference) between different substances.
III. Physical and Chemical Changes
A. A physical change occurs when a material changes without a chemical reaction (change in shape, phase, color). Examples: cutting objects, boiling/freezing/melting water, painting an object a different color
B. A chemical change occurs when a new substance forms through a chemical reaction. It can be shown as a formula:
Reactants→ Products (Example: CH4 + 2O2 → CO2 + 2H2O)
Methane + Oxygen yields Carbon Dioxide + Water
Examples: burning, cooking/baking, creating gas by mixing chemicals, digesting food, rust forming, food rotting/spoiling
C. The Law of Conservation of Mass states that the total number of each atom has to be the same before and after a reaction (matter is
not created or destroyed)
I. Observations and Inferences
A. Observations are made using the senses (sight, taste, touch, smell, hearing)
B. Observations can be quantitative (numbers or measurements) or qualitative (colors, texture).
C. Inferences are conclusions based on observations.
II. Characteristics of Organisms (living things)
A. Includes the following: made of cells, use energy, maintain homeostasis, genetics (DNA), grow and develop, evolve (have adaptations), reproduce, respond to stimuli
B. Key terms include:
Homeostasis: the maintenance of a stable internal environment (examples: body temperature, heart rate)
Adaptations: behaviors or structures that help organisms survive (examples: hibernating, gills, fur)
Stimuli (stimulus): may cause a response
(examples: a hot stove, cold air, light)
Metabolism: converting food into energy
III. Scientific Method
A. Series of steps taken to investigate a question or problem
B. Usually includes identifying a problem, researching, testing a hypothesis
-A hypothesis (if, then, because statement) is an educated prediction that can be tested by conducting an experiment.
C. The last step is often to “form a conclusion” based on the data (information collected).
IV. Experiments (collecting data)
A. Contain only 1 independent variable (the difference between the groups or trials)
B. Contain a dependent variable (the observation that is measured)
C. Contain multiple control variables (stay the same in all groups or trials)
D. Valid (reliable) if they can be duplicated (repeated) by others, and the same result is found to occur.
V. Organizing Data (charts and graphs)
A. Charts list data or information in a logical order.
-On a chart, the independent variable is usually on the left and the dependent variable is usually on the right
B. Graphs show trends visually (in science line graphs and bar graphs are common)
-On a graph, the independent variable is on the X axis and the dependent variable is on the Y axis
-If the graph shows something occurring “over time”, then time goes on the X axis.