Do Now… Copy the HW & list as many elements as you can think of (without looking at a periodic table) HOMEWORK – Write a pre-lab for tomorrow’s separation of sand and salt lab.

ELEMENTS Element – a substance that cannot be broken down into other substances by chemical methods.  the simplest form of matter that has a unique set of properties.  examples – gold, neon, copper, astatine, carbon, bromine…

EVERYTHING ON THE PERIODIC TABLE IS AN ELEMENT!!!

COMPOUNDS Compound – a substance composed of a given combination of elements that can be broken down into those elements by chemical methods  ALWAYS contains DIFFERENT elements  examples – magnesium oxide (MgO), water (H 2 O), sodium chloride (NaCl)…

Compounds can be broken down into simpler substances by chemical methods, but elements cannot.  Ex: When sugar is heated,it goes through a chemical change. Breaking Down Compounds

 Final products = carbon and water vapor  Can then break down H 2 O into H 2 and O 2 using electricity

Properties of Compounds In general, the properties of compounds are quite different from those of their component elements.  chlorine (Cl 2 )is used to kill harmful organisms in swimming pools.  sodium vapor (Na) produces the light in some street lamps.  sodium chloride (NaCl), commonly called salt, is used to season or preserve food.

Mixtures & Pure Substances How can pure substances and mixtures be distinguished?  A pure substance ALWAYS has the same composition.  Must be an element or a compound.  Ex: water, silver  A mixture has a variable composition.  Must be a mixture of compounds and/or elements.  Ex: air, granite, chicken noodle soup

TYPES OF MIXTURES HOMOGENEOUS the same throughout also called a solution Ex: salt water, brass HETEROGENEOUS NOT the same throughout different properties in different parts of the same mixture Ex: sand & water, granite

REVIEW OF 3-4 (Mixtures & Pure Substances) 1. Is milk a mixture or pure substance? 2. What do you think about chocolate milk? Homogeneous mixture. It’s a mixture of water, sugar, fats and proteins that is usually the same composition throughout. Heterogeneous mixture. It’s a mixture of water, sugar, fats, proteins & cocoa that usually has a lot more chocolate on the bottom of the glass than at the top… YUMMY

REVIEW OF 3-3 (Elements & Compounds) 3. Passing an electric current through a certain substance produces oxygen and sulfur. This substance cannot be a(n) a) compound. b) mixture. c) element. d) solution

REVIEW OF 3-3 (Elements & Compounds) 4. Which of the following is a mixture? a) sodium chloride b) carbon dioxide c) sucrose d) air

REVIEW OF 3-2 (Chemical vs. Physical Change) 1. TRUE or FALSE: Heating water, causing it to boil is a chemical change. FALSE…Liquid water becomes gaseous water when it boils, but it’s still H 2 O! (this is a physical change) Chemical changes occur when different substances are produced.

REVIEW OF 3-2 (Chemical vs. Physical Change) 5. A substance’s ability to change into different substances is called a: a) physical property b) physical change c) chemical property d) chemical change

REVIEW OF 3-2 (Chemical vs. Physical Change) 6. Classify the following as chemical or physical changes: a) gold melting b) natural gas burning c) crushing an aluminum can d) leaves turning colors in the fall PHYSICAL CHEMICAL

REVIEW OF 3-1 (States of Matter) 7. Which of the following states of matter takes the shape of its container and has a fixed or definite volume? a) solid b) liquid c) gas d) plasma

REVIEW OF 3-1 (states of matter) 8. Rank the three most commonly cited states of matter from highest to lowest energy: a) solid, liquid, gas b) liquid, gas, solid c) solid, gas, liquid d) gas, liquid, solid