do now! september 25, 2012

Do Now!September 25, 2012Another T-chart!!!!!!!!!!!!!Another T-chart!!!!!!!!!!!!!It’s the last one…. For now.It’s the last one…. For now.

• Which are physical properties?• Which are chemical properties?

Temperature Color Tarnish (think jewlery)Melting Point Odor HardnessRusting Amount

Combustion (think gasoline)

THEN… Work on the Ch. 13 Sec. 1 ASSESSMENT QUESTIONS pg. 545

Physical Properties Chemical Properties

WednesdaySeptember 26, 2012

Fe2O3 What is the ratio of atoms of iron (Fe) to atoms of oxygen (O) in this compound?

Iron to oxygen is ____ to _____Iron:oxygen = _____:____

What about for the compound AlCl3? What is the compound and what is the ratio of atoms?

ThursdaySeptember 27, 2012

Find the volume of your science Find the volume of your science textbook and of another textbook and of another

object at your desk (of your object at your desk (of your choosing). List ALL steps on choosing). List ALL steps on

your Do Now page.your Do Now page.Rulers are on my desk.Rulers are on my desk.

Do the following problems:*Remember!* write every step of the problem!!

V = L x W x HD = m/V

What is the density of a piece of wood that has a mass of 25.0 grams and a volume of 29.4 cm3?

The density of water is 1 g/cm3. A piece of wood that measures 3.0 cm by 6.0 cm by 4.0 cm has a mass of 80.0 grams. What is the density of the wood? Would the piece of wood float in water? (volume = L x W x H)

What is the density of a piece of wood that has a mass of 25.0 grams and a volume of 29.4 cm3?

A piece of wood that measures 3.0 cm by 6.0 cm by 4.0 cm has a mass of 80.0 grams. What is the density of

the wood? Would the piece of wood float in water? (volume = L x W x H)

I threw a plastic ball in the pool for my dog to fetch. The mass of the ball was 125 grams. What must

the volume be to have a density of 0.500 g/mL. ( I want it to float of course!)

Measuring Matter

Chapter 13Chapter 13Section 2Section 2

DiscussDiscuss (by raising your hands, people)

How do we measure matter?

What do we use to measure matter?

What is the difference between weight and mass?

A riddle…

Which weighs more, a pound of feathers, or

a pound of sand?

….. They weigh the same! One pound!

Weight & Mass

• Suppose you want to measure your weight.• As you step on a scale, your body weight

presses down on the springs inside.• The more you weigh, the more the springs

compress, causing the pointer on the scale to turn farther, giving a higher reading.

• If you took this exact scale to the moon, would it indicate the same weight?

Weight

Your weight is a measure of the force of gravity on you.

On Earth, all objects are attracted toward the center of the planet by

the force of Earth’s gravity.

MassThe mass of an object is the measurement

of the amount of matter in the object.

If you travel to the moon, the amount of matter in your body – your mass – does

not change.

? ? ?

Does anyone know why the moon has such a small

gravitational pull?

Because………….

the mass of the moon is so much smaller than the mass of the Earth! Because of this, the moon exerts much less gravitational force on you.

Units of MassTo measure the properties of matter, scientists

use a system called the International System of Units.

Also known as… “SI” (because of its French name, Système International)

UnitsThe SI unit of mass is the kilogram (kg).

If you weigh 90 pounds on Earth, your mass is about 40 kilograms.

A smaller unit that is also used is the gram (g).

How many grams are in a kilogram?

1000

Why do scientists prefer to describe matter by

its mass?Unlike weight, mass does not change with location, even

when the force of gravity on an object changes.

VolumeAll matter has mass and takes up space… right?

RIGHT!

The actual amount of space that matter occupies is

called its volume.

Units of Volume

Common units of volume include…*liter (L)*milliliter (mL)*cubic centimeter (cm3)

Units of Volume1 L = 1,000 mL1 mL = 0.001 L1 mL = 1 cm3

Calculating VolumeVolume of solid objects = cubic centimeters (cm3)

[usually]

Volume = Length x Width x Height

5 cm20 cm

9 cm

What is the volume of this brick?900 cm3

How could you measure the volume of an apple?

Submerge the apple in water in a graduated cylinder. The water level will rise by an amount that is equal to the volume of the object in milliliters.

Density• Samples of two different materials may have

the same volume, but they don’t necessarily have the same mass.

A kilogram of

sand takes up

much less space

than a kilogram

of feathers.

The volumes differ because sand and feathers have different densities.

Density relates the mass of a material in a given volume.

This is often expressed as the number of grams in one cubic centimeter.

For example, the density of water at room temperature is expressed as “one gram per cubic centimeter (cm3).”

Every gram of water has a volume of 1 cm3

Math in Science?!

Density = mass . volume

This bar (between the ‘g’ and the ‘cm3’) tells you that you can determine the density of a sample of matter by dividing its mass by its volume

1 g/cm3

Sinking or Floating?

Imagine you have a solid block of wood and a solid block of iron. You drop both into a tub of water. Do they float? Do they sink? What happens?Wood floats! (think of a boat…)

Iron sinks! (think of an anchor…)

Objects with _______________ densities than water will sink.

Objects with _______________ densities than water will float.

lesser

greater

Using Density

Density is a _____________ property of a substance. (physical or chemical??)

Because of this, density can be used to __________ an ____________substance.

physical

identify unknown

Imagine you are out hiking, and you find a shiny, golden-colored rock. How would you know the

rock is gold or fool’s gold?

• Look up the _________________ of gold.

• Measure the ________________ and __________________ of the rock to find its ________________.

• If the ______________ matches the amount that you looked up, you have a match!

Happy October!Happy October!Monday October 1, 2012

• Calculate your weight as it would be on the moon.

– Your weight would be only one sixth (.167) of your weight on Earth.