Science AHSGE Standard II

Objective 2- States of Matter

Matter

• Anything that has mass and takes up space – Kinetic Molecular Theory: Matter is made of atoms

which are in constant motion– Temperature- Average movement of particles (kinetic

energy)– Change in temperature (motion of particles) = change in

state of matter

• States of Matter:– Solids– Liquids– Gases– Plasma

Plasma

• 99% of known matter in universe- stars and other planets

• No definite shape; particles broken apart

• Ionized gas• Appears to be solid• Conducts electricity• Affected by magnetic and

electric fields

Solids

• Definite shape; does not take shape of container

• Definite volume; always same amount of space

• Atoms tightly packed together in rows

• Vibrate slowly back and forth in place

• Lowest kinetic energy

Characteristics of Solid

• Malleability- Ability to be hammered into thin sheets– Ex: Gold flattened into jewelry

• Elasticity- Ability to stretch and return to original position– Ex: Rubberband

• Brittleness- Ease with which it breaks– Ex: Glass is more brittle than

steel

• Hardness- Ability to resist scratching– Ex: Diamond is harder

than soap

• Tensile strength- Resistance to breaking under pressure– Concrete withstands

hitting while paper may tear

Liquids

• Definite volume• No definite shape; takes

shape of container• Molecules loosely packed

together• Particles able to slide past

one another• More kinetic energy than

solids

Density and Floating

• Density = mass (g)Volume (ml)

• Solids tend to be more dense than liquids of the same substance; liquids more than gas

• In order for an object to float, its density must be less than the liquid it is in

• Example: Density of water = 1 g/ml– 0.34 g/ml stick floats– 2 g/ml stick sinks

Characteristics of Liquids

• Viscosity- Resistance of a liquid to flow (thickness)– Syrup is more viscous than

water

• Surface tension- Tendency to form a skin on the surface when sitting still– Ponds develop and water

bugs jump on

• Cohesion- Particles of the same substance sticking together– Water molecules stick together

to flow

• Adhesion- Particles of different substances sticking together– Water molecules sticking to

sides of glass graduated cylinder forming a meniscus

Gases

• No definite volume; completely fills all space available

• No definite shape; takes entire shape of closed container

• Particles repel each other; very far apart

• Most kinetic energy; fast movement

• Expands (increase in volume) when heated & vice versa