Term |
Definition |
Matter |
made up of extremely small particles that make up atoms ; molecules that are always in motion. |
All matter |
has energy. |
Matter |
anything that has mass ; volume. |
meter |
SI unit for measuring length |
grams (or kilograms) |
SI Unit for measuring mass |
liters |
SI Unit for measuring volume |
Scientific method |
set of steps scientists use to answer questions and solve problems. |
Densest liquids |
settle to the bottom of a container |
Least dense liquids |
float on top of container |
Density of water |
One |
Chemical changes |
the composition of matter changes. |
Physical changes |
do not change the composition of matter. |
Crystalline solids |
have particles in repeating patterns of rows |
Amorphous solids |
have an irregular pattern of particles. |
Three properties of Gases |
Have particles that are 1) very fast moving 2) spread far apart 3) have no definite shape or volume. |
Evaporation |
liquid becomes a gas. E.g. Puddle of water becoming water vapor |
Condensation |
gas to a liquid. E.g. water drops on a cold glass |
Compound |
Two or more elements join together chemically to form a new substance. |
Two examples of chemical properties |
1) flammability and 2) reactivity to oxygen or acid. |
Soluble |
Substance can be dissolved in water. |
Solutions |
Formed when two or more substances are evenly mixed. |
Speed is determined by what two factors |
distance and time. |
Velocity is determined by what 3 factors |
1) distance 2) time and 3) direction. |
Balanced forces |
Have a net force of Zero Newtons. |
Gravitational force |
Determined by mass and distance. |
The greater the mass |
the greater the gravity (e.g. sun [large] vs moon [small]). |
The closer the distance |
the stronger the gravity (e.g. sun's pull on Earth vs Pluto). |
The Law of Conservation of momentum |
states that when objects collide the total amount of momentum stays the same. |
(In the absence of air resistance) why do all objects fall to the ground at the same rate |
Because the acceleration due to gravity is the same for all objects on earth. |
Newton’s 1st law of motion (law of inertia) |
an object at rest will remain at rest / an object in motion will remain in motion at a constant speed and in a straight line unless acted on by an unbalanced force. |
Atom |
The smallest particle which an element can be divided and still be the same substance. |
Nucleus of an atom is |
dense ; positively charged. |
Electrons are where? |
In the electron cloud. |
Isotopes |
Atoms that have the same number of protons but a different number of neutrons. |
groups or families |
Vertical columns on the periodic table |
periods |
horizontal rows on the periodic table |
Metals |
Elements to the left of the zigzag line of the periodic table. |
Nonmetals |
Elements to the right of the zigzag line of the periodic table (these make up the majority of the elements in the periodic table). |
Metalloids |
Elements that scatter either side of the zigzag line of the periodic table |
Mendeleev |
Arranged the elements by increasing atomic mass |
Henry Mosley |
Arranged the current periodic table by increasing atomic number. |
How can you tell a chemical change has occurred |
a new substance with different properties from the original substances is formed. |
Reactants |
are before the arrow in a chemical equation |
Products |
are after the arrow in a chemical equation. |
The Law of Conservation of Mass |
Mass cannot be created nor destroyed in a chemical reaction. |
When counting atoms |
if no subscript is written it is assumed to be one atom. |
Acids |
1) have a sour taste ; 2) turn blue litmus paper red. |
Bases |
1) have a bitter taste 2) feel slippery ; 3) turn litmus paper blue. |
pH above 7 |
bases. |
pH equals 7 |
neutral |
pH below 7 |
acids |
Why are telescopes put in space |
to avoid interference from Earth’s atmosphere. |
One rotation of Earth happens |
Every 24 hours. |
365 ? days (1 year) |
One revolution (orbit) of Earth around the sun |
29 ? days (1 month) |
One orbit of moon around the Earth |
Color of a star depends on |
its temperature. |
Phases of the moon are caused by |
the relative positions of the moon Earth and the sun. |
Total solar eclipse |
when the shadow of the moon falls on the Earth. |
How did the moon form |
A large planet sized body struck the Earth – called the Collision Ring Theory. |
Why do we only see one side of the moon (the near side) |
The moon’s period of rotation is equal to its period of revolution |