Structure & Properties of Simple Molecular Substances

Structure & Properties of Simple Molecular Substances

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Multiple Choice

What is a molecule?

• Groups of atoms bonded by metallic bonds.

• Groups of atoms which are ionically bonded

• Atoms which are bonded by sharing electron pairs

Multiple Choice

What type of bonding exists between the non-metal atoms in a molecule?

• Ionic bond

• Van der Waals

• Metallic bond

• Covalent bond

Multiple Choice

What forces exist between molecules?

• Strong intermolecular forces

• Strong electrostatic forces

• Weak intermolecular forces

• Weak electrostatic forces

Multiple Choice

Which of the following is NOT a simple molecular substance?

Multiple Choice

What is the job of intermolecular forces?

• To expel the molecules away from each other

• To hold the molecules together

• To move the electrons between molecules

• To hold the atoms together in a molecule

Structure of Simple Molecular Substance

• Consist of small covalent molecules

• The atoms within the molecules are held together by STRONG COVALENT BONDS

• Weak forces (INTERMOLECULAR FORCES) exist between molecules

• Molecules are distinct and separated from other molecules

Structure of Simple Molecular Substance

• Substances with simple molecular structures maybe solids, liquids or gases at room conditions.

• This includes elements such as hydrogen, oxygen and bromine.

• And compounds such as water and carbon dioxide.

Multiple Choice

Molecules are made of ____.

• atoms bonded by ionic bonds

• atoms held by intermolecular forces

• atoms bonded by covalent bonds

• atoms bonded by metallic bonds

Multiple Choice

Molecules are ____.

• bonded together with other molecules

• are made up of ions

• distinct and separate

• held by a strong intermolecular force

Multiple Choice

Which is NOT an example of simple molecular substance?

• CO₂

• NaCl

• O₂

• CH₄

Physical Properties of Simple Molecular Substances

• Physical State

• Melting and Boiling Points

• Volatility

• Electrical Conductivity

• Solubility

Physical State

• Most substances are liquids or gases at room temperature.

• As the forces between the molecules are weak, the molecules are not held together tightly like the particles in a solid.

• Molecules are free to move.

Melting and Boiling Points

• Usually have low melting and boiling points

• Only the weak intermolecular forces BETWEEN the molecules are overcome when heated.

• During melting or boiling, the molecules separate, the atoms in the molecules DO NOT.

Melting and Boiling Points

• Simple molecular substances are held by weak intermolecular forces called VAN DER WAALS forces.

• The strength of intermolecular forces increases (Van der Waals forces) as the size of molecules increase.

• As the size of molecules increase, the melting and boiling points increase.

Multiple Choice

Simple molecular substances are usually _____ at room temperature.

• solids

• liquids or gases

• liquids only

• solids, liquids and gases

Multiple Choice

Simple molecular substances ____.

• have high melting and boiling points

• have medium melting and boiling points

• have low melting and boiling points

Multiple Choice

Molecules have intermolecular forces ____.

• between the atoms

• between the ions

• between the molecules

Multiple Choice

Intermolecular forces are ____.

• very strong

• stronger than covalent bonds

• very weak

Multiple Choice

Intermolecular forces need ___.

• a lot of energy to break

• no energy to break

• a little amount of energy to break

Open Ended

What happens to the strength of the intermolecular forces as the size of the molecules increases?

Multiple Choice

What happens to the strength of the intermolecular forces as the size of the molecules increases?

• increases

• decreases

• remains the same

Open Ended

As the size of molecules increase, what happens to the melting and boiling point?

Volatility

• Many covalent compounds have low boiling points.

• They are volatile and evaporate easily to give a smell.

• The forces between covalent molecules in perfumes are very weak and easily broken.

• When the perfume evaporates, covalent molecules escape and the perfume can be smelled from a distance.

Electrical Conductivity

• Substances with a simple molecular structure DO NOT conduct electricity.

• To conduct electricity, substances must contain either IONS or ELECTRONS that are FREE TO MOVE.

• Molecules DO NOT contain either.

• Some molecular substances are used as electrical insulators.

Solubility

• Most molecular substances are INSOLUBLE in water.

• Most dissolve in organic solvents.

• LIKE DISSOLVES LIKE

• Polar molecules dissolve polar molecules, nonpolar molecules dissolve nonpolar molecules.

• Polar molecules are structures having an uneven distribution of electron density.​

Multiple Choice

Polar molecules are

• structures having an uneven distribution of electron density.

• structures having an equal distribution of electron density.

Multiple Choice

Volatility means

• ability of a substance to evaporates readily at normal temperature.

• ability of a substance to turn in to solid.

• ability of a substance to become liquid from gaseous state.

Multiple Choice

Simple molecular substances are volatile because ___.

• the atoms are held by weak intermolecular forces

• the atoms are held by strong intermolecular forces

• the molecules are held by weak Van der Waals forces

• the molecules are held by strong Van der Waals forces.

Multiple Choice

Simple molecular substances ___.

• can conduct electricity

• cannot conduct electricity

Multiple Choice

Substances can only conduct electricity if ___.

• particles are free to move

• particles are charged

• particles are static

• particles are charged and free to move

Multiple Choice

Nonpolar molecules are

• structures having an uneven distribution of electron density.

• structures having an equal distribution of electron density.

Multiple Choice

Most molecular substances are insoluble in water because ____.

• most molecular substances are polar just like the water

• most molecular substances are nonpolar unlike the water which is polar

Multiple Choice

What type of bonding exists between the non-metal atoms in a molecule?

• Ionic bond

• Van der Waals

• Metallic bond

• Covalent bond

Poll

For this lesson, I am confidently sure that I have understood all the topics!

• Strongly agree

• Agree

• Neither agree or disagree

• Disagree

• Strongly disagree