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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 (H2O), 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
Breaking Down Compounds
Final products = carbon and water vapor
Can then break down H2O into H2 and O2 using electricity
Properties of CompoundsIn general, the properties of compounds are quite different from those of their component elements.
chlorine (Cl2)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 chlorideb) carbon dioxidec) sucrosed) 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 H2O!
(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 propertyb) physical changec) chemical propertyd) 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 burningc) crushing an
aluminum cand) leaves turning
colors in the fall
PHYSICAL
PHYSICAL
CHEMICAL
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) solidb) liquidc) gasd) 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, gasb) liquid, gas, solidc) solid, gas, liquidd) gas, liquid, solid