Monday, February 23

• Pick up the “Reviewing Matter” notes slip and glue it into your comp book.

• Pick up your scale tracking form and open to your scale. • Highlight or underline everything you FULLY understand on

your scale in your comp book.• Shade and date your current scale level. BE ACCURATE.• On the lines below, answer the following: My goal score on

the Matter Unit Test is ______ and I will achieve that score because I will _____________________________________

• Return your scale form to the bin when finished.• Pick up your vocab poster and continue working on it.

Kinetic Theory of Matter

Matter is made up of particles which are in continual random motion.

Energy

• Atoms/Molecules/Particles all have ENERGY• Remember energy and the law of

conservation of energy?

• Energy = the ability to do work or cause change

• Energy can transform into different forms, but it isn’t created or destroyed

Review

Temperature: measure of average kinetic (moving) energy of particles in a substance

Pressure• a Force per unit area. Measured with a barometer• With gases the force comes from the gas

molecules hitting the side of the container.

• Gas pressure is a gauge of the number and force of collisions between gas particles and the walls of the container that holds them.

• The SI unit for pressure is the pascal (Pa)

Chemical Changes

Evidence of a chemical reactionFormation of gas Formation of precipitate Change in color Change in energy

Endothermic Absorbs heat energy (gets cold) Exothermic Releases heat energy (gets hot)

Chemical Changes

Atoms are re-arranged, NOT created or destroyed

Law of Conservation of Matter

Matter is conserved type of atoms does not change

Nothing is created or destroyed

Law of Conservation of Mass

Mass is conserved amount of atoms cannot change

Nothing is created or destroyed

DENSITY & BUOYANCY

BUOYANCY

• BUOYANCY = the ability to float in a fluid.

• Examples of fluids = water, air• BUOYANT FORCE = the upward

force that acts on a submerged object.– It acts opposite of gravity

WEIGHT OF OBJECT

BUOYANT FORCE

THE BIGGER FORCEWINS, SO THE BLOCK

SINKS

Which one is easier to pick up?Why?

This beach ball floats.Why?

Because the Buoyant Force is greaterthan the weight of the ball.

ARCHIMEDES’ PRINCIPLE

The buoyant force acting on a submerged object is equal to the

weight of the fluid the object displaces.

ARCHIMEDES’ PRINCIPLE states that the WEIGHT of the amount of

water displaced is equal to the BUOYANT FORCE.

WHICH ONE IS MORE LIKELY TO FLOAT?

BA

Mass = 90 kg Mass = 90 kg

DENSITY

DOESN’T DENSITY HAVE SOMETHING TO DO WITH IF SOMETHING SINKS OR

FLOATS?

DENSITY

d = m / v

DENSITY OF WATER = 1 g/cm3

• If the object has a higher density, it sinks.• If the object has a lower density, it floats.• if the object has the same density, it flinks

(floats in the middle of the water).

DENSITY & BUOYANCY

• Having a lower density than water means that the beach ball’s buoyant force is higher than the weight of the beach ball.

WATER

SO THE BEACHBALL FLOATS.

DENSITY & BUOYANCY

• Having a higher density than water means that the cinder block’s buoyant force is lower than the weight of the cinder block.

WATER

SO THE CINDERBLOCK SINKS.

DENSITY & BUOYANCY

• Having the same density as water means that the boot’s buoyant force is equal to the weight of the boot.

WATER

SO THE BOOTNEITHER SINKSNOR FLOATS, ITFLINKS

CHANGING DENSITY

You can change an object’s density by:

1. Increasing/decreasing its mass

2. Increasing/decreasing its volume

mvd =

AN OBJECT FLOATS

CAUSES:• Weight is less than the buoyant force.• Object is less dense than the fluid• Object decreases its mass and becomes

less dense than the fluid.• Object increases its volume and

becomes denser than the fluid.

AN OBJECT SINKS

CAUSES:

1. Weight is greater than the buoyant force.

2. Object is denser than the fluid

3. Object increases its mass and becomes denser than the fluid.

4. Object decreases its volume and becomes denser than the fluid.