dcp review #2 part 1

Front

What is an element?

Back

An element is a pure substance that cannot be broken down into simpler substances by chemical means. Examples include Oxygen (O), Hydrogen (H), and Carbon (C).

Front

Which of the following is an example of an element: H2O, H2, NaCl, or CaCO3?

Back

H2 is an example of an element, as it consists of only hydrogen atoms.

Front

What is a physical change?

Back

A physical change is a change that affects one or more physical properties of a substance without altering its chemical composition. Examples include melting, freezing, and breaking.

Front

What is a chemical change?

Back

A chemical change occurs when a substance transforms into a different substance with different properties. Examples include rusting, burning, and cooking.

Front

What happens to a chocolate bar when it melts?

Back

Melting a chocolate bar is a physical change because it changes from solid to liquid but retains its chemical composition.

Front

What is the difference between a physical change and a chemical change?

Back

A physical change affects the form of a substance, while a chemical change results in the formation of new substances.

Front

What is the formula for water?

Back

The formula for water is H2O, which consists of two hydrogen atoms and one oxygen atom.

Front

What is the formula for table salt?

Back

The formula for table salt is NaCl, which consists of sodium (Na) and chlorine (Cl) ions.

Front

What is the significance of the periodic table?

Back

The periodic table organizes all known elements based on their atomic number, electron configuration, and recurring chemical properties.

Front

What is an example of a physical property?

Back

An example of a physical property is color, boiling point, or density.