An Introduction to Chemical Concepts Chemistry In this lesson, we will discuss the following: Chemical Size Properties Changes Naming Compounds.

An Introduction to Chemical Concepts

Chemistry

In this lesson, we will discuss the following:

Chemical Size

Properties

Changes

Naming Compounds

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Let’s Do a Crossword

Puzzle!

Categorizing Chemicals by Size

• SUBMICROSCOPIC: Anything which is too small to be seen with an optical microscope is considered to be submicroscopic.

• MICROSCOPIC: Anything that is too small to be seen with the naked eye but is large enough to be seen with an optical microscope is considered to be microscopic.

• MACROSCOPIC: Anything that is large enough to be seen with the naked eye is considered to be macroscopic.

Categorizing Chemicals by Size

In chemistry, we will be discussing microscopic and submicroscopic particles, and how they affect what we see in the macroscopic world.

Properties

We will discuss two kinds of properties:• Physical Properties• Chemical Properties

Physical Properties

• PHYSICAL PROPERTIES are defined as properties which can be observed without changing a substance into another substance (or group of substances).

Examples of physical properties:

• Melting point• Color• Luster

• Hardness• Texture

Chemical Properties

• CHEMICAL PROPERTIES are defined as properties that can be observed only by changing one substance into a new substance (or group of substances).

Examples of chemical

properties:

• Tendency to react with water• Tendency to

combust• Tendency to

decompose

• Physical and chemical properties can be divided into two smaller categories:– Intensive properties and– Extensive properties.

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chemical properties.

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Changes

We will discuss two kinds of changes:• Physical Changes• Chemical Changes

Physical Changes

• A PHYSICAL CHANGE changes some characteristic (or characteristics) of a substance without actually changing what the substance is.

Chemical Changes

• A CHEMICAL CHANGE (or chemical reaction) is the change of a substance into a new substance (or group of substances).

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chemical changes.

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Chemical Changes

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• The atoms present before a chemical change are still present after the chemical change.

• The atoms are just rearranged to form new substances.

This is called the Law

of Conservation of Mass.

Chemical Changes

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The transformation of oxygen, O2, into ozone, O3, is an example of

A. a physical change.B. a chemical change.C. both a physical and chemical change.D. neither a physical nor chemical change.

O=O

O=O

O=O

OO

O O

O

O

oxygen ozone

The transformation of oxygen, O2, into ozone, O3, is an example of

A. a physical change.B. a chemical change.C. both a physical and chemical change.D. neither a physical nor chemical change.

O=O

O=O

O=O

OO

O O

O

O

oxygen ozone

Elements Versus Compounds

• ELEMENTS: An element is defined as a substance made of only one kind of atom.

• COMPOUNDS: A compound is defined as a substance made of two or more kinds of atoms in a CHEMICAL combination.– A compound is made of elements, but a

compound is uniquely different from the elements which make it up.

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Which of the following boxes contains an element? A compound?

A B C

A. Element: A, C Compound: A, B, C

B. Element: C Compound: A, B

C. Element: C Compound: B

D. Element: A, C Compound: A, B

Which of the following boxes contains an element? A compound?

A B C

A. Element: A, C Compound: A, B, C

B. Element: C Compound: A, B

C. Element: C Compound: B

D. Element: A, C Compound: A, B

Naming Compounds• IONIC COMPOUNDS: An ionic

compound is a substance made of a negatively-charged ion chemically combined with a positively-charged ion.– Many ionic compounds are made of

one kind of metal ion and one kind of nonmetal ion.

• COVALENT COMPOUNDS: A covalent compound is a substance made of more than one nonmetal combined chemically.

An ION is just an atom

with a net charge.

Naming Type I Ionic Compounds

A Type I ionic compound is made up of a metal and a nonmetal. Only metals which form ions with one charge take part in forming Type I ionic compounds.

Naming Type I Ionic Compounds

In order to name a Type I ionic compound, you should do the following:1. Write down the name of the metal atom first.

The metal atom is farther left on the Periodic Table than the nonmetal atom.

2. Write down the name of the nonmetal atom next. Give the name an “ide” suffix.

Naming Type I Ionic Compounds

Example:What is the name of LiBr?

Solution:

Lithium bromideWrite down the name of

the metal atom first.

Next, write down the

name of the nonmetal

atom. Give the nonmetal

the “ide” ending.

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with naming ionic

compounds.

Naming Covalent Compounds

• A covalent compound is made of two or more nonmetals in a chemical combination.

Naming Covalent Compounds

When naming a covalent compound, you should do the following:1. Write the name of the first kind of atom in

the chemical formula. Use the appropriate prefix if necessary.

2. Write the name of the second kind of atom in the chemical formula. Use the appropriate prefix if necessary, and use the “ide” suffix.

• Some of the suffixes used when naming covalent compounds follow:– Mono = 1– Di = 2– Tri = 3– Tetra = 4– Penta = 5– Hexa = 6– Hepta = 7– Octa = 8

Naming Covalent Compounds

• The prefix “mono” should not be used with the first atom in a covalent compound.

Naming Covalent Compounds

Example:Name the following compound:

CO

Naming Covalent Compounds

Solution:

Carbon monoxide

Write down the name of

the first atom. Use the

appropriate prefix if

necessary.

Next, write down the

name of the second atom.

Give it the appropriate

prefix if necessary

and the “ide” ending.

Example:Name the following compound:

CO2

Naming Covalent Compounds

Solution:

Carbon dioxide

Write down the name of

the first atom. Use the

appropriate prefix if

necessary.

Next, write down the

name of the second atom.

Give it the appropriate

prefix if necessary

and the “ide” ending.

Example:Name the following compounds:

H2O and H2O2

Naming Covalent Compounds

Solution:

Dihydrogen monoxide

andDihydrogen dioxide

Write down the name of

the first atom. Use the

appropriate prefix if

necessary.

Next, write down the

name of the second atom.

Give it the appropriate

prefix if necessary

and the “ide” ending.

Sometimes Common Names are Used for Compounds

Example:Name the following compounds:

H2O and H2O2

Or, they are calledWater

andHydrogen peroxide

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with naming covalent

compounds.