M IDTERM R EVIEW Chemistry

C HAPTER 1 T HE S CIENCE OF C HEMISTRY PG 4-9 Chemistry – the study of matter and how it interacts with other matter Chemical – any substance that has a definite composition. A chemical is always made of the same “stuff” no matter where it comes from

E XAMPLES OF C HEMICALS

C HEMICALS Not all chemicals are bad. Chemicals are necessary for every day life.

S TATES OF M ATTER Three states of matter: Solid Liquid Gas

S OLIDS Have a fixed volume and definite shape. Atoms are held tightly in rigid structure and vibrate only slightly

L IQUIDS Have a fixed volume and indefinite shape Can easily take the shape if its container

G ASES Indefinite volume and indefinite shape Atoms are held very loosely together

P RODUCTS VS R EACTANTS Products are what come out of a reaction Reactants are what are put into the reaction

R EACTANTS : H 2 AND N 2 P RODUCT : NH 3

D ESCRIBING M ATTER S ECTION 2 PG Matter - anything that has mass and volume List of non-matter: Time Sound Sunlight Thoughts Gravity Microwaves Heat Memories Reflections Energy

V OLUME VS M ASS Volume – is the amount of space an object takes up Mass – the amount of matter in an object OgkVE

V OLUME VS M ASS Volume is measured in liters, gallons, or some unit cubed (cm 3, m 3, in 3 ) Mass is measured in grams

M EASURING V OLUME Fill a graduated cylinder and read the lines. The lines measure mL Just like the lines on a ruler measure cm

W HAT IS THE VOLUME OF THIS LIQUID ?

W HAT IS THE MASS OF THIS LIQUID ?

D ETERMINING M ASS Mass is measured in grams. To find the mass of something, you must you a scale or balance.

M ASS VS W EIGHT Weight is the force produced by gravity acting on a mass. The mass of an object never changes. Weight varies depending on gravity.

D ENSITY Density – is the ratio of mass to volume of an object. How much “stuff” is in an object compared to how much space it takes up. Density = Mass/Volume

D ENSITY Density can be used to identify substances Every pure element has a specific density that does not change

S ECTION 3 H OW IS MATTER CLASSIFIED ? P G Atoms – the smallest unit of an element that maintains the properties of that element

P URE SUBSTANCE Pure substances are either elements or compounds. Pure substances have definite chemical and physical properties

E LEMENTS Are substances that cannot be broken down into anything else. Composed of only one type of atom

C OMPOUNDS Composed of more than one type of atom. Still have definite properties. Examples : H 2 O CO 2 C 12 H 6 O 12

M IXTURES Do not have definite compositions or definite properties Examples: Salt Water Sand Sugar Water

H ETEROGENEOUS VS H OMOGENEOUS Homogeneous – mixture is distributed uniformly throughout Heterogeneous – mixture is not distributed uniformly throughout