Elements, Compounds, Mixtures

Elements, Compounds, Mixtures

Learning Outcomes

• recognize that substances be classified as elements, compounds and mixtures

• state that elements are the basic building blocks of all matter

• recognize that elements are classified according to their properties

• classify elements as metals and non-metals based on their characteristic properties

What are elements?

• An element is a pure substance that cannot be broken down into any simpler substances by chemical method

• An example of chemical method is electrolysis

Multiple Choice

Which element is not a noble gas?

• argon

• helium

• oxygen

• neon

Multiple Choice

Which element is a halogen?

• carbon

• nitrogen

• oxygen

• fluorine

The Periodic Table of Elements

• Each element is represented by a symbol.

Multiple Choice

Which element has the symbol Na?

• nitrogen

• neon

• sodium

• nickel

Multiple Choice

Fe is the symbol for which element?

• fluorine

• francium

• iron

• xenon

Multiple Choice

What is the symbol for silver?

• Ag

• Au

• S

• Si

Classifying elements by state at room temperature

• 11 elements are gases, e.g. nitrogen, oxygen and chlorine

• 2 elements are liquids, mercury and bromine

• all other elements are solids

Multiple Choice

Which of the following is the definition of an element?

• It is a pure substance that can be broken down into simpler substances by chemical methods.

• It is a pure substance that can be broken down into simpler substances by physical methods.

• It is a pure substance that cannot be broken down into simpler substances by chemical methods.

• It is an impure substance that cannot be broken down into simpler substances by chemical methods.

Multiple Select

Select the statements that are true.

• There are two elements that are gases and 11 elements that are liquids.

• Two elements that are liquids at room temperature are mercury and bromine.

• Elements in Group 0 are called noble gases.

• Elements in Group I are called transition metals.

• Elements in Group VII are called halogens.

Classifying elements as metals and non-metals

• Most metals are solids at room temperature. Exception: mercury is a liquid at room temperature.

• Non-metals may be solids, liquids or gases at room temperature.

Classifying elements as in the Periodic Table

• Elements are arranged in order of the proton (atomic) number of the respective atoms.

• Elements in the same group have similar properties (e.g. low density, are coloured, etc., reactive, etc.)

Multiple Choice

Which of the following elements is not a gas at room temperature?

• krypton

• sulfur

• nitrogen

• chlorine

Multiple Choice

Metals are found on the left of the Periodic Table while non-metals are found on the right of the Periodic Table.

• True

• False

Multiple Select

Select the metals from the list below.

• bromine

• aluminium

• titanium

• lithium

• silicon

Multiple Choice

Mercury is the only metal that is a liquid at room temperature.

• True

• False

Multiple Select

Select the properties of non-metals.

• good conductors of heat and electricity

• brittle

• usually dull and soft

• ductile

Multiple Choice

Elements in the same period have similar properties.

• True

• False