science test

matter flowchart

matter flowchart

heterogeneous mixture examples-

• dirt

• salad dressing

• blood

homogeneous mixture examples

• saltwater

• lemonade

• air

• iced tea

• fruit punch

• milk

compoud examples

• water

• carbon dioxide

• salt

• calcium nitrate

element examples

• silver

• gold

• platinum

• hydrogen

• oxygen

matter

takes up space or has mass

heterogeneous mixture

composition is different throughout

homogeneous mixture

composition is the same throughout

mixture

combination of elements & compounds

pure substance

constant composition

element

cannot be broken down

compound

2 or more elements chemically combined

molecule

2 or more atoms chemically combined

atom

smallest unit that makes up an element

boiling point

temperature where a liquid turns to gas

temperature

measures energy of molecules

melting point

temperature where a solid turns to liquid

sublimation

solid turns to gas (dry ice)

condensation

when a gas turns to liquid

vaporization

liquid turns to gas

what is the difference between chemical and physical changes?

physical: composition doesn’t change (reversible)

chemical: composition of material changes (irreversible)

physical changes examples

• dissolving

• boiling

• cutting paper

chemical changes examples

• digesting food

• explosion

• fermentation

why doesn’t a solid flow?

the molecules are compact and only vibrate

similarities between a gas and liquid

• the molecules flow

• they have no definite shape

main difference between mixtures and pure substances

pure substances cannot be broken down by physical means while mixtures can

what is chromatography and how does it work

technique used to separate dissolved chemicals

dyes travel different distances based on their attraction to water

if you double the size of the chromatography strip, would the retention factor change?

no, the end results (fractions) would simplify down to the same numbers

what is the between chemical and physical properties

physical - identifiable without changing the chemical identity (5 senses)

chemical - evident after a chemical change

physical properties

• blue color

• melting point

• luster

chemical properties

• flammable

• supports combustion

• reacts with acid

intermolecular force

force that holds atoms together within a molecule

solids have the highest intermolecular force because the atoms are the most compact