Science

precipitate

A SOLID THAT FORMS from a solution during a chemical reaction

chemical change

change that produces new substances

compound

substance formed by the chemical combination of two or more elements in definite proportions

chemical property

the ability of a substance to undergo a specific chemical change

density

the amount of matter in a given space

What is the difference between a mixture and a compound?

A mixture is made of two or more substances that are not chemically combined whereas a compound is made of 2 or more elements that are chemically combined.

What is the difference between an atom and a molecule?

An atom is the smallest amount you can have of an element whereas a molecule is the smallest amount you can have of a compound. A compound is made of atoms.

Describe 5 physical properties of water.

Boling point: 100°C Odor: odorless Flammability: nonflammable Density: 1.00g/cc Color: clear

Explain the difference between a chemical change and a physical change. What are some indications or signs that a chemical change has occurred?

In a physical change, the identiy of the substance does not change; it simply changes form. When a chemical change occurs, new substances with new identities and properties are created.

Can the composition of a compound vary?Explain

No. The elements that make up the compound are combined in fixed ratios. For example, water is always two atoms of hydrogen and one atom of oxygen.

Can the composition of a mixture vary? Explain.

Yes. The amounts of the various components in the mixture can vary relative to each other. For example,a person could add one or two spoons of sugar to their coffee.

element

any substance that cannot be made smaller/

colloid

heterogeneous mixture whose particles never settle

molecule

smallest unit of most compounds

conductivity

the ability of a material to allow either heat or electricity to flow through it

How is density calculated? What are the units?

D=m/v ; g/cc

Separation techniques (Filtration, Distillation)

Filtration requires that one substance is soluble in the liquid and one is insoluble. Distillation requires that one substance has a different boiling point than the other substance

solution

A homogeneous mixture of two or more substances

physical change

a change in a substance that does not involve a change in the identity of the substance

physical property

a characteristic of a substance that can be observed without changing the substance into another substance

flammability

the ability of a substance to burn

reactivity

the ability of a substance to react chemically

heterogeneous mixture

the parts of the mixture are noticeably different from one another

filtration

the process whereby fluids pass through a filter

melting point

the temperature at which a solid becomes a liquid

boiling point

the temperature at which a substance changes from a liquid to a gas

What is the difference between a compound and an element? Give two examples of each.

A compound is a combination of 2 or more elements that are chemically bound together. An element is just a single element. Sodium chloride (NaCl) is a compound and iron (Fe) is an element

pure substance

a substance with constant composition

malleability

the ability of a substance to be hammered or beaten into thin sheets

What is the difference between a heterogeneous mixture and a homogeneous mixture? Give an example of each

In a heterogenous mixture, it is possible to see the various components. You can tell it is made up of more than one substance. An example is sand at the bottom of a beaker of water. A homogeneous mixture looks like it is just one substance. You cannot notice that is made up of different substances. An example is milk or Gatorade

atom

Smallest unit of an element

What are three types of homogeneous mixtures? Give an example of each

Solution: koolaid powder dissolve in water Suspension: clay powder suspended in water Colloid: fog, homogenized mil

distillate

a concentrated liquid produced by boiling a liquid mixture and then condensing its vapor

suspension

a heterogeneous mixture that separates into layers over time

distillation

a liquid is boiled to produce a vapor that is then condensed into a liquid

viscosity

a liquid's resistance to flow

homogeneous mixture

a mixture that is the same throughout

characteristic property

a property that always stays the same