The Nature of The Nature of MatterMatter

K 1.2 The Simplest MatterK 1.2 The Simplest Matter

The Simplest MatterThe Simplest Matter

An element is matter made of only An element is matter made of only one kind of atom. one kind of atom.

At least 115 elements are known At least 115 elements are known and about 90 of them occur and about 90 of them occur naturally on Earth. naturally on Earth.

The other elements are known as The other elements are known as synthetic elements. synthetic elements.

The elements are organized on the The elements are organized on the periodic table by their properties.periodic table by their properties.

The Simplest MatterThe Simplest Matter

The rows in the table are called The rows in the table are called periods. The elements in a row periods. The elements in a row have the same number of energy have the same number of energy levels. levels.

The columns are called groups. The columns are called groups. The elements in each group have The elements in each group have similar properties related to similar properties related to their structure.their structure.

The Simplest MatterThe Simplest Matter The top number is the element's atomic The top number is the element's atomic

number.number. It tells you the number of protons in the It tells you the number of protons in the

nucleus of each atom of that element. nucleus of each atom of that element. Isotopes (I suh tohps) are atoms of the same Isotopes (I suh tohps) are atoms of the same

element that have different numbers of element that have different numbers of neutrons. neutrons.

An atom's mass number is the number of An atom's mass number is the number of protons plus the number of neutrons it protons plus the number of neutrons it contains.contains.

The atomic mass is the weighted average The atomic mass is the weighted average mass of the isotopes of an element.mass of the isotopes of an element.

The Simplest MatterThe Simplest Matter Metals generally have a shiny or Metals generally have a shiny or

metallic luster and are good metallic luster and are good conductors of heat and electricity. conductors of heat and electricity.

All metals, except mercury, are solids All metals, except mercury, are solids at room temperature.at room temperature.

Metals are malleable which means Metals are malleable which means they can be bent and pounded into they can be bent and pounded into various shapes. various shapes.

Metals are also ductile, which means Metals are also ductile, which means they can be drawn into wires without they can be drawn into wires without breaking.breaking.

Gold - Au

Nickel - Ni

Mercury - Hg

The Simplest MatterThe Simplest Matter

Nonmetals are elements that are Nonmetals are elements that are usually dull in appearance. usually dull in appearance.

Most are poor conductors of heat Most are poor conductors of heat and electricity. and electricity.

Metalloids are elements that have Metalloids are elements that have characteristics of metals and characteristics of metals and nonmetals. nonmetals.

Some metalloids are shiny and Some metalloids are shiny and many are conductors.many are conductors.

Silicon - Si

Carbon - CHelium - He