Learning Objectives - World of Chemistry · 3/1/2010 1 created by Ms Janelle Tay\2010 1 Learning...

$: Learning Objectives - World of Chemistry · 3/1/2010 1 created by Ms Janelle Tay\2010 1 Learning Objectives • Define what elements, compounds and mixtures are. • Give the names$
3/1/2010

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1created by Ms Janelle Tay\2010

Learning Objectives

• Define what elements, compounds and mixtures are.

• Give the names and symbols of common elements.

• State how elements are classified.

• State what the building block of an element is.

• Describe the differences between compounds and mixtures.


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What is an element?

• An element is a _________________ which is made up of ____________________.

• Refer to your periodic table for the list of elements available now.

• An element _____________________________________by chemical methods.

pure substance

1 type of atom only

cannot be broken down into simpler substances

- E.g. Gold Ring is made of the element gold, which consists of gold atoms.


How do we represent elements?

• Each element has a _______ and ______________________.

• The symbol for an element consists of either one or two letters.

• **NOTE: The first letter is a capital letter while the second is a small letter.

Mg mg mG MG

name

chemical symbol


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Mini-Quiz Part 1

What are the chemical symbols of the following elements?

(a) Bromine

(b) Silver

(c) Uranium

(d) Antimony

(e) Tungsten

Br

Ag

U

Sb

W


Mini-Quiz Part 2

What are the names of the elements with the following chemical symbols?

(a) Si

(b) P

(c) Sn

(d) Pb

(e) Au

Silicon

Phosphorus

Tin

Lead

Gold


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How do we classify elements?

• Classification of elements by ________

– Their physical state at _____________________

• Examples:

Solid state Liquid StateGaseous

State

state

room temperature

Sodium

Magnesium

Mercury Oxygen

Hydrogen


How do we classify elements?

• Classification of elements as ____________________

Metals Non-metals

- Shiny appearances - Dull appearances

- High Densities - Low densities

- High melting and boiling point - Low melting and boiling points

-Good thermal and electrical conductors - Poor thermal and electrical conductors

- Ductile - Non-ductile

- Malleable - Brittle

- Sonorous - Non-sonorous

Physical Properties of Metals and Non-metals

metals and non-metals


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Elements Made up of…

Sodium

Copper

Argon

Hydrogen

Oxygen

Iodine

Sodium atoms

Copper atoms

Argon atoms

Hydrogen molecules

Oxygen molecules

Iodine molecules


Molecular Drawing of ElementType of element Diagram

Monatomic element

E.g. Elements from Group 8

Helium (He), Neon (Ne)

Metals

E.g. Zinc, Copper

Molecules

E.g. hydrogen gas, oxygen gas


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Molecules

• A molecule is a group of ____________________that are ________________________(joined together).

• Example: Oxygen gas, hydrogen gas.

Oxygen gas

two or more atomschemically combined


Mini-Quiz

A pure element is made up of one type of atom only.

Thinking Process!


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What is a Compound?

• A compound is a substance which is made up of ___________________________ _________________________. – E.g. Water H20

– Sodium chloride NaCl

– Calcium carbonate CaCO3

Sodium chloride

2 or more types of elements

chemically joined together


Compounds

• The ratio of the number of different atoms in a compound is _________.

• E.g. A water molecule is always made up of 2 hydrogen atoms and 1 oxygen atom.

fixed


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Compounds

• The properties of a compound ________ from the properties of the individual elements from which it was originally formed.

• There is usually some form of energy _________ or __________ when a compound is formed.

Methane gas

differs

given out taken in


CompoundsCompound Chemical

formulaMade up of…

Water H2O

Carbon dioxide C02

Methane CH4

Sodium chloride NaCl

Silver nitrate AgNO3

Carbon dioxide molecules

Water molecules

Sodium ions and

chloride ions

Methane molecules

Silver ions and

nitrate ions


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Mixtures

• Mixtures are formed when two or more substances are added together withoutchemical bonds being formed.

• Mixtures can be made up of elements and compounds.

• The components of a mixture

are not fixed.


Examples of Mixtures

• Milo Dinosaur

• Ingredients: Milo powder, water, milk, sugar

• The amount added for each ingredient is not fixed!


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Examples of Mixtures

Mixture Made up of…

Air Different gases (e.g. oxygen, nitrogen, carbon dioxide, etc)

Salt solution Salt (sodium chloride) and water


Molecular Drawing of Mixtures

Type of Mixture Diagram

A mixture of two elements e.g. Neon (Ne) and Hydrogen (H2)

A mixture of two compounds e.g. water (H2O) and sodium chloride (NaCl)

A mixture of one element and one compound e.g. Argon (Ar) and carbon monoxide (CO)


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Differences between a mixture and a compoundMixture Compound

Separation Components of a mixture can be separated by physical methods, e.g. filtration.

Elements in compound can only be separated by chemical reactions.

Composition No fixed composition Has a fixed composition by mass

Properties The chemical properties of a mixture are the same as those of its components.

The physical and chemical properties of a compound are different from those of the elements in the compounds.

Energy Change No chemical reaction takes place when a mixture is formed – usually there is little or no energy change.

A chemical reaction takes place when a compound is formed –usually there is an energy change (e.g. the reactants get hot).


Exercise


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Exercise


Learning Objectives - World of Chemistry · 3/1/2010 1 created by Ms Janelle Tay\2010 1 Learning...

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