Matter & Chemistry
What is chemistry?
Chemistry is the study of matter.
What is an element?
An element contains only one type of atom and cannot be decomposed into simpler substances.
What is a physical change?
A physical change occurs when the composition of the substance remains unchanged.
What is the SI unit for mass?
Kilogram (kg)
How many significant digits are in 8341?
4 significant digits
What are two requirements for something to be matter?
Matter has mass and occupies space.
i.e., we can measure its mass on a balance
i.e., It is physically present in three dimensions
What is a compound?
A compound contains more than one type of atom or element.
What is kinetic energy?
Kinetic energy is energy of motion, while potential energy is stored energy.
What is the SI unit for temperature?
Kelvin (K)
How many significant digits are in 0.00079?
2 significant digits
What is a molecule?
A molecule is a combination of two or more atoms joined by covalent bonds.
What is the difference between a heterogeneous and homogenous mixture?
A homogeneous mixture has uniform composition; a heterogeneous mixture has non-uniform composition.
What phase change is solid -> gas?
Sublimation
What does the prefix kilo- mean?
1,000 or 103
How many significant digits are in 1200.00043?
9 significant digits
What is an ion? Give an example.
A ion is an electrically charged atom or groups of atoms. Examples include Na+ and Cl-.
Give an example of a heterogeneous mixture.
Seawater
Concrete
The atmosphere
Oil and water
Sand and water
Salad
What happens to atoms/electrons during a chemical reaction?
A chemical reaction involves rearrangement of atoms/electrons, converting the initial substances into different substances.
Convert 1 km into meters.
1 km = 1 x 103 m = 1000m
How many significant digits are in 400.?
3 significant digits
What holds the atoms in a molecule together?
Atoms in a molecule are connected by covalent bonds.
What is a solution?
A solution is a homogeneous mixture of more than one substance, usually involving a solvent.
Name three forms of energy.
Gravitational
Electrical
Chemical
Thermal
Radiant
A student needs to convert 2.5 km into meters. Using dimensional analysis, what is the final answer?
2,500 m
2.5 km x (1000 m / 1 km) = 2,500 m
Round 3.7500 to the appropriate value using the "nearest even digit" rule.
3.8