Lecture 2: Matter, Elements and Compounds, States of Matter, Physical and Chemical Changes

ELEMENTS AND COMPOUNDS STATES OF MATTERPHYSICAL AND CHEMICAL PROPERTIES AND CHANGES

Lecture for 9/11/2007

What is matter?

Anything that has mass and volume

Ancient Greece and India – intrigued by the origin of matter and the makeup of the universe

Is there anywhere that doesn’t contain matter?

States of matter

Solid – holds a particular shape and has definite volume

Liquid – doesn’t hold its own shape but it does occupy a definite volume

Gas – has no definite shape or volume Plasma – exists inside stars and forms

briefly on Earth when electrical sparks separate atoms into their component parts.

Changes in state - Heating or cooling a substances

Properties of matter

Physical properties Characteristics of a substance that can be

observed without altering the identity of the substance

Chemical properties Characteristics of a substance that cannot be

observed without altering the substance

Physical and Chemical Changes

Physical changes – changes that don’t alter the identity of a substance

Chemical changes – alter the identity of the substance

Identify the following as physical or a chemical change:

Sugar ferments to form alcohol. Gallium metal melts in your hand. Platinum reacts with hydrogen peroxide

oxygen at room temperature. Leaves turn color in the Fall.

Identify the following as physical or a chemical change CON’T:

Milk turns sour. Wax is melted over a flame and then

catches fire and burns. You make scrambled eggs. You step on a piece of chalk and it

becomes powdered. You light a candle when the electricity

goes out. Steam from your hot shower condenses

on a cold mirror.

Law of conservation of matter

Antoine Lavoisier (1743 – 1794)

Matter, like energy, is neither created nor destroyed in any process

Elements and Compounds

Distinguishing Between Elements and Compounds

Both elements and compounds are pure substances

Difficult to determine when a more “fundamental” element was reached

Tear apart substances to see if a more simpler element can be reached