Compounds And Elements

Objectives:3.3 Describe a pure substance as a

compound or an element, after conducting an experiment.

3.4 Analyze a compound.

Classification: Everything in the world that has a mass

is called “matter” Matter can be classified as:

Matter

Pure Substance Mixture

Element Ex. gold

Compound Ex. water

Hetero-geneous Mixture

Homo-geneous Mixture

Matter:anything that takes up space & has a

mass

Ex. a deskEx. pizzaEx. silver necklaceEx. oxygen

Mixture: combinations of two or more substances

that are not chemically combined (mixed)Easily separatedEx. fruit saladEx. sugar in coffee

Pure Substance: composed of a single substance with the

same properties throughoutEx. waterEx. table salt

simplest form of matter

cannot be separated or broken down into simpler substance

Ex. Oxygen Ex. Aluminum Ex. Gold Ex. Copper

A pure substance can be further broken down into an element or a compound……Elements:

substance made of two or more elements

can be separated into simpler substance

Ex. Water (H2O) Ex. Carbon dioxide (CO2) Ex. Sugar (C6H12O6) Ex. Salt (NaCl)

Recall, a pure substance can be further broken down into an element or a compoundCompounds:

NOTE:With chemical reactions you can go from an element to compound & vise versa!!!

Element Compound

HO

Ex. oxygen & hydrogen

Ex. water (H2O)

H

OH H

Recall, a mixture can be further broken down into a homogeneous mixture or a heterogeneous mixture……

Homogeneous Mixture:Mixture that looks uniform throughout or

like one substance

Ex. milk in coffeeEx. sugar dissolved in water

Heterogeneous Mixture:mixtures that are not uniformcan see individual parts

Ex. saladEx. chocolate chip muffin

State whether the following are examples of an

element or a compound.

A gold ringRust (Fe2O3)Carbon monoxide (CO)Aluminum FoilCalcium

element compound

compound element element

State whether the following are examples of an element or a

compound or a mixture

A blueberry muffinChunky SoupSalt (NaCl)Helium Water (H2O)

mixture mixture compound elementcompound

Element Compound Mixture Compound

State whether the following pictures represent an element or a compound or a mixture

Which statement best describes a compound.

A) A pure substance that has a high melting point.

B) A mixture that is formed by two or more elements.C ) A pure substance that is formed by two or more elements.

Reactions:Chemical Reactions can combine

elements to make compounds (synthesis reaction)

OR

Chemical Reactions can break apart compounds into its elements(decomposition reaction)

Synthesis Reaction:

Makes a new substance Sign of a chemical change Increase in mass Ex.

Ex.

If you see mass, the ONLY thing

you know is that a compound was

made!!!

+

+

Decomposition Reaction:

Two or more substances produced Sign of a chemical change Decrease in mass Ex.

Ex.

If you see mass, the

ONLY thing you know is

that you started with

a compound!

+

+

You a leave a 2g copper penny outside. Over time, the penny becomes green in color & its mass is now 2.5g.

Which statements below are true?A) A chemical change occurredB) A physical change occurredC) A compound was made

TRUE

TRUED) An element was made

You have 5g orange powder which you heat. As the powder is heated you noticed that a gas is given off & a silver liquid is produced. After heating you only have 1g of the orange powder left.

Which substance was definitely a compound? Why?

orange powderdecrease in mass production of two

substances

A grey colored solid is heated. The following observations were recorded

Before Heating After HeatingState solid solidColor grey blackTexture smooth granularMass 1.75g 2.5g

What statement is DEFINITELY true?A) The solid after heating is an elementB) The solid after heating is a compoundC ) The solid before heating is an element

TRUE

A) The white powder could be an element

In a lab you heat 50g of a white powder in an open container. Over time, you obtain a yellow substance with a mass of 65g.

Which statement is FALSE?

B) The white powder could be a compoundC) The yellow substance could be an elementD) The yellow substance could be a compound

Mixture: 2 or more components brought together that

can be separated physically Pure Substance

A single substance with the same properties throughout

Element Simplest form of matter that can not be

broken down Compound

2 or more elements chemically combined

To identify elements or compounds:

If mass increases, you know that you have made a compound

If mass decreases, you know that you started with a compound

Activities

Physical Science Worksheet #3 Student Study Guide- Module 1.19

to 1-22 Other Activities:

Science Quest Textbook – page 31 – 33

References

Student Study Guide – Physical Science 416/436 - MEQ

Science Quest – Grenier, Daigle, Rheaume – 1998, Cheneliere

http://www.elmhurst.edu/~chm/vchembook/101Aatoms.html

http://www.elmhurst.edu/~chm/vchembook/103Acompounds.html

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