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Molecules as Lewis Structures

Random Molecule Questions

Making Molecules Simulation

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Molecule overview: Atoms are the basic building blocks of matter, and they can join together to form molecules. Molecules are new types of matter with different properites.

A molecule is a group of atoms that are held together by covalent bonds. Atoms may be identical or different.

Molecules with different elements are called compounds. For example, a water molecule is made up of two hydrogen atoms and one oxygen atom, which are bonded together. Its formula is H2O.

Background: Lewis-structure models represent molecules. Each element in a molecule is represented by its chemical symbol. Electrons are represented as dots. Lines are drawn between atoms to show covalent bonds; each line/bond connects two single electrons. Excess electrons are represented as pairs of dots and are placed next to the atoms.

HONC is a good way to remember how many covalent bonds each element makes.

Memorize these 12 common molecules drawn as Lewis Structures:

Hydrogen Gas – H2

Diatomic Elemental Molecule

Most abundant element in the universe

Oxygen Gas – O2

Diatomic Elemental Molecule

You need to breathe this in to live.

Water – H2O

Dihydrogen Monoxide

Compound

You are 65% water

Hydrogen Peroxide – H2O2

Compound

You put this on a wound. It can make your dog puke.

Nitrogen Gas – N2

78% of air

Ammonia Gas – NH3

Compound

In cleaners. Makes fertilizers.

Carbon Dioxide Gas - CO2

Compound

You breathe this out. Another greenhouse gas.

Methane Gas – CH4

Compound

A Greenhouse Gas - from sewage, compost and cow bellies.

Ethylene Gas – C2H4

Compound

Ripens Fruit

Precursor to polyethylene, a type of plastic

Acetylene Gas – C2H2

Used in blow torches!

Compound

Three bonds means hot flames!

Propane Gas - C3H8

Compound

We use this to grill food.

Glucose! C6H12O6

Glucose is stored chemical energy. Your cells use it by burning it with O2.

You exhale CO2 and H2O as products of cellular respiration.

Glucose is a compound.

Glucose molecule

Gilbert Newton Lewis

Gilbert Newton Lewis (October 25, 1875 – March 23, 1946) was an American physical chemist known for the discovery of the covalent bond and his concept of electron pairs; his Lewis dot structures and other contributions to valence bond theory have shaped modern theories of chemical bonding.

Dr. Lewis developed a method of drawing the structure of molecules. Molecules drawn with this method are referred to as Lewis Structure Molecules.

Gilbert Newton Lewis

This is a Methane Gas Molecule shown as a Lewis structure.

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Making Molecules Simulation

Different elements make a different number of covalent bonds. You can see the different number of bonds each element makes below:

1 = Hydrogen makes 1 covalent bond

2 = Oxygen makes 2 covalent bonds

3 = Nitrogen makes 3 covalent bonds

4 = Carbon makes 4 covalent bonds

Covalent Bonds

Covalent means "sharing outer electrons."

A covalent bond ties two atoms together. Each bond his made of two electrons.

For instance, Hydrogen atoms bond together using a covalent bond. Once bonded, each Hydrogen atom has a complete shell and is very happy.

They have formed a hydrogen molecule.

Here you can see how two hydrogen atoms make a covalent bond to make a hydrogen gas molecule.

A molecule consists of two or more atoms that bond by sharing their outer (valence) electrons.

2 electrons make covalent bond. To the right you will see a Lewis Structure model of hydrogen gas.

This hydrogen molecule has one covalent bond. The bond has 2 electrons.

Some Chemistry Vocabulary that Relates to Molecules

Hydrogen Atom

Atom = The smallest unit of matter; The basic unit of a chemical element. For example, Water (H2O) is made up of three atoms.

Water Molecule

An element is composed of one kind of atom. An element is a pure substance. An element cannot be broken down by physical or chemical means.

90 elements occur naturally on Earth. The other 19 or so are made in the lab. This means that in the universe, there are only 90 different types of atoms that make everything. C, H, O, N and P are the primary elements that make up living organisms.

Compound = a chemical substance that is formed from two or more elements, that bond in a fixed ratio.

For example, water (H2O) is a compound that is composed of two hydrogen atoms for every oxygen atom.

NH3, HCl, H2O2, SiO2, CH4, C2H2, and C2H4, are compounds. In contrast, O2 is not a compound because it is only made of one element. A compound is a pure substance.

This diagram shows the difference between diatomic elements and compounds.

Covalent Bonding is where 2 or more atoms bond by sharing their outer electrons. Generally, covalent bonds are made between nonmetal atoms. The result of this bond is a molecule.

Covalent means, "Sharing outer electrons." The nucleus of an atom is never changed or altered after bonding. Covalent bonding allows atoms to complete their outer shells.

This is a nitrogen gas molecule.

Electrons are stable subatomic particles that have a negative charge. They can be found in the shells of atoms outside the nucleus.

A pair of electrons form a covalent bond between atoms. Electrons are involved in chemical reactions.

A molecule consists of two or more atoms that bond by sharing their outer electrons.

You will see a Lewis Structure model of a water molecule to the right:

This is a Lewis Structure Model of water.

Water (H20) is a molecule. It is also a compound because it is made up of two different elements.

10 Molecules You Should Know.pptx

Neutrons are a subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen. Neutrons help to keep the nucleus of an atom together. Neutrons are like glue that hold the positive nucleus together.

The octet rule states that after bonding...

8 electrons surround all atoms in columns 4-7. (After bonding)
Hydrogen's outer ring is completed with 2 electrons. (After bonding)
All atoms have a complete outer ring. All electrons are paired up. (After bonding)
All atoms have a complete outer ring like noble gasses. (After bonding)

In summary: Atoms share or transfer their electrons with other atoms to complete their outer ring and be like the noble gasses.

Protons: The number of protons in the nucleus determines what the element is. For instance, atoms with one proton are the element hydrogen. Atoms with 8 protons are the element of Oxygen.

Protons are stable subatomic particles that are found in the nucleus of all atoms. Protons have a positive charge and counteract the charge of electrons.

Subatomic Particles = particles smaller than an atom. Protons, neutrons and electrons are subatomic particles. In other words, they are particles that are smaller than the atom.

The symbol for the element oxygen is O.

Symbol: Elements have been given a symbol. The symbol consists of one, two or three letters. H = Hydrogen, O = Oxygen, N = Nitrogen, C = Carbon.

If there is more than one letter for the symbol, only the first letter is capitalized. For example, Helium = He.

The symbols for some elements have been known since ancient times and are derived from their Latin names. Ex: Potassium (K) is Kalium in Latin. Sodium (Na) is Natrium in Latin.

Valence electrons are electrons outside filled rings or shells. They are the outer electrons.

Carbon has 4 valence electrons. Nitrogen has 5 valence electrons. Oxygen has 6 outer electrons. Hydrogen has 1 outer electron.

Some other Lewis Structures to admire:

Hydrochloric Acid - HCl

Compound

In your stomach

Fluorine Gas – F2

Compound

Highly reactive and toxic.

Silicon Dioxide – SiO2

Compound

Quartz sand - Precursor to Glass and computer chips.

Random Molecule Questions

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