Science chapter 1 section 1 n 2

Science chapter 1 section 1 n 2

Element

Pure substance with one type of atom

Compound

Two or more elements chemically combined.

Substance

Either an element or compound.

Mixture

Two or more substances physically combined.

Heterogeneous mixture

Different materials can be distinguished.

Homogeneous mixture

Substances are evenly spread out.

Solution

Another name for a homogeneous mixture.

Solution particles

Too small to see with a microscope.

Does solution particles settle

No, they never settle.

How do solutions stay mixed

Constantly and uniformly.

Colloid

Tiny particles evenly distributed in another substance.

Colloid appearance

Murky or opaque.

Why do colloids scatter light

Particles are large enough to scatter light.

Colloid example

Fog and car headlights.

Do colloids separate?

Generally not on standing.

Can filtration separate colloids?

No

Tyndall effect

Scattering of light by mixture particles.

Tyndall effect examples

Sunlight shining through dusty air.

Another Tyndall effect example

Headlights visible on foggy nights.

Suspension

Heterogeneous mixture with visible particles that settle.

Suspension example:

Snow globe

Physical property

Observed without changing the substance

Purpose of physical property

Observe and describe matter.

Physical properties

Color, odor, texture, density, melting point, boiling point, solubility.

Why are physical properties important?

They distinguish substances.

Physical change

Change in size, shape, or state.

Do physical changes change identity?

No

Chemical change

One substance changes into a different substance.

Chemical property

Shows whether a substance can undergo chemical change.

Chemical property ex

Flammability, combustion, reactivity with water, pH.

What is conservation of mass?

Total mass of products equals total mass of reactants.