Mid-Year Review

Chemistry, Earth History, Infectious Disease, Lithosphere

Chemistry 8.P.1 Understand the properties of matter and changes that occur when interacts in an open and closed container.

Physical & Chemical Properties:

Physical Properties: Odor, Density, Mass, Volume, State, Color. Can be observed or measured without the item being changed.

Chemical Properties: Flammability, Re-activity. These properties can only be observed during a chemical reaction.

Physical & Chemical Change:

Physical Change: Does not form a new substance.

Chemical Properties: One or more substances are changed into new substance that have new & different properties.

Elements, Compounds & Mixtures:

Elements: Made up of one type of atom. Cannot be separated into similar substances by physical or chemical means. Located on the Period Table of Elements.

Compound: Are made up of 2 or more atoms of different elements that are bonded together. Made of elements in a specific ratio that are always the same. Has a chemical formula that can only be separated by chemical means.

Mixtures: Combination of 2 or more pure substances that are held together by physical forces, not chemical. No chemical change takes place.

Periodic Table:

There are 7 periods on the Periodic Table & there are 18 groups.

Group 1: Alkali Metals- Extremely reactive, never found in nature has its pure form. Density is extremely low.

Group 2: Alkaline-earth Metals: Slightly less reactive than Alkali Metals.More dense than Alkali Metals.

Groups 3-12: Transition Metals: Moderate range of reactivity & a wide range of properties. Good conductors of heat & electricity. They have higher densities and melting points than groups 1&2.

Lanthanides & Actinides: They are also transition metals but placed at the bottom of the Periodic Table so it wouldn't be so wide. The lanthanides are shiny & reactive. All actinides are radioactive and therefore very unstable. Elements 95-103 do not exist in nature but have been manufactured in the lab.

Group 13: Boron Group: Most abundant metal in the earth's crust. Contains one metalloid and 4 metals. Reactive. Aluminum is in this group.

Group 14: Carbon Group: Contains one nonmetal, two metalliods, & one metal. Varied reactivity.

Group 15: Nitrogen Group: Contains two nonmetals, one metalliod, & one metal. Varied reactivity.

Group 16: Oxygen Group: Contains three nonmetals, one metalliod, & one metal. Reactive group (6 outer level electrons)

Group 17: Halogens: All nonmetals. Very reactive. Poor conductors of heat & electricity. Tends to form salts with metals. Ex. NaCl: Sodium chloride also known as "table salt". (7 outer level electrons)

Group 18: Noble Gases: Nonreactive nonmetals. All are colorless, odorless gases at room temperature. Found in earth's atmosphere in small amounts (8 outer level electrons)

The groups are the numbers going horizontally & the periods are the numbers going vertically. The rate of reactivity goes from the far left, being the most reactive, and the far right, being the least reactive.

Nonmetals, metalliods, & metals are all located in the far right of the Periodic Table.

Atomic Number: The atomic number is the top number located on any box in the Periodic Table. For example, Hydrogen's atomic number is 1.

Atomic Mass: The atomic mass is the bottom number on any box in the Periodic Table. For example, Hydrogen's atomic mass would be 1.008.

Protons & Electrons: The number of protons & electrons is the same number as the atomic number. For example, Hydrogen's atomic number is 1 so this element has 1 proton & 1 electron.

Neutrons: To find the number of neutrons, you have to first round the atomic mass and subtract that by the atomic number. For example; Hydrogen's rounded atomic mass is 1. 1-1=0. So Hydrogen has 0 neutrons.

Law of Conservation of Mass: The law of conservation of mass states that matter can not be added or removed, only changed. The mass must stay consistent.


Solution: A substance made as a result of mixing a solid and a liquid and the solid dissolves.

Matter: Anything that has mass and takes up space.

Mixture: Combination of two or more different substances that is mixed but not combined.

Element: Building blocks of matter made up of atoms.

Atom: The basic building blocks for all matter.

Earth History

Law of Superposition: Younger rocks lie above older rocks if the layers have not been disturbed.

Index Fossils: A fossil that is found in the rock layers of only one geologic age and is used to establish the age of the rock layers.

Ice Cores: Ice core is a core sample from an ice sheet used to compare the climate of today and those years back.

Geologic Time Scale: Used by geologists to describe the timing and relationships between events that have occurred throughout earth's history.

Relative & Absolute Dating: Absolute dating is the exact age of the fossil. Relative dating is used to determine the age of a fossil by looking at its position in layers of sedimentary rocks.

Half Life/Radioactive Decay: Half life is the time required for half of a substance that makes up a living organism to disintegrate (decay or break down). & The Radioactive Decay is a method used by geologists to determine the age of a fossil.


Uniformitarianism: The idea that laws and processes that happen on earth have always happened and continue to happen everywhere in the universe.

Fossil Record: A record of the total number of fossils that have been discovered.

Isotopes: Different versions of the same element.

Geology: The study of the origin, history, and the structure of the earth.

Infectious Diseases

Microorganisms: Uni-cellular, Microscopic, Very diverse.

Virus: A small non-living particle that invades and then reproduces inside a living cell.

Bacteria: Bacteria are prokaryotes. The genetic material in their cells is not contained in a nucleus.