The Composition, Structure, and Properties of Substances

Front

Which of the following is an example of a pure element? Water (H₂O), Solid Gold (Au), Saltwater, Air

Back

Solid Gold (Au)

Answer explanation

Solid Gold (Au) is a pure element, consisting only of gold atoms. In contrast, Water (H2O) is a pure compound, and Saltwater & Air both mixtures, containing multiple substances.

Front

What distinguishes a pure compound from a mixture?

Back

Pure compounds have specific atomic compositions, structures, and properties.

Front

Mixture

Back

A mixture is a sample of matter containing more than one substance.

Front

What forms when a metal bonds with a non-metal?

Back

an Ionic Crystal

Front

What type of bond involves the sharing of electrons between non-metals?

Back

Covalent bond

Front

Example of a covalent substance forming a crystal: Sodium chloride (NaCl), Magnesium Oxide (MgO), Frozen Water (H₂O), Calcium Chloride (CaCl₂)

Back

Frozen Water (H₂O)

Front

What is the main difference between atomic composition and chemical structure?

Back

Atomic composition is about the types and numbers of atoms, while chemical structure is about the shape formed how the atoms are connected.

Answer explanation

Atomic Composition is the types and numbers of atoms in a substance. For example, water (H₂O) has two hydrogen atoms and one oxygen atom, while hydrogen peroxide (H₂O₂) has two hydrogen atoms and two oxygen atoms. These differences can change a substance’s properties.

Chemical Structure: is the shape formed by the way atoms are connected in a molecule. Even if the atoms and their amounts are the same, differences in structure can cause molecules to have very different properties. Like how Butane and Isobutane are both C₄H₁₀ yet have different properties.

Front

Which two molecules have the same atomic composition but different chemical structures?

Back

Butane and isobutane

Answer explanation

Butane and isobutane are structural isomers, meaning they have the same atomic compositions (C4H10) but different shapes or chemical structures. Water and hydrogen peroxide have different atomic compositions, H2O vs H2O2.

Front

How does Splenda™ (sucralose: C₁₂H₁₉Cl₃O₈) differ from ordinary sugar (sucrose: C₁₂H₂₂O₁₁)?

Back

Sucralose and sugar have a similar chemical structure, but a different atomic composition.

Answer explanation

Sucralose and sugar have a very similar shape or chemical structure. However, Sucralose and sugar have different atomic composistions. Sucralose has chlorine atoms replacing some (OH) groups in sucrose, causing to distinct properties.

Front

Appearance (in the context of testing the properties of a substance)

Back

The way a substance looks, including its color, shape, size, and texture