The Nature of Matter

1. The Nature of Matter K 1.2 The Simplest Matter

2. The Simplest Matter • An element is matter made of only one kind of atom. • At least 115 elements are known and about 90 of them occur naturally on Earth. • The other elements are known as synthetic elements. • The elements are organized on the periodic table by their properties.

4. The Simplest Matter • The rows in the table are called periods. The elements in a row have the same number of energy levels. • The columns are called groups. The elements in each group have similar properties related to their structure.

6. The Simplest Matter • The top number is the element's atomic number. • It tells you the number of protons in the nucleus of each atom of that element. • Isotopes (I suh tohps) are atoms of the same element that have different numbers of neutrons. • An atom's mass number is the number of protons plus the number of neutrons it contains. • The atomic mass is the weighted average mass of the isotopes of an element.

8. The Simplest Matter • Metals generally have a shiny or metallic luster and are good conductors of heat and electricity. • All metals, except mercury, are solids at room temperature. • Metals are malleable which means they can be bent and pounded into various shapes. • Metals are also ductile, which means they can be drawn into wires without breaking.

9. Nickel - Ni Gold - Au Mercury - Hg

10. The Simplest Matter • Nonmetals are elements that are usually dull in appearance. • Most are poor conductors of heat and electricity. • Metalloids are elements that have characteristics of metals and nonmetals. • Some metalloids are shiny and many are conductors.

11. Silicon - Si Carbon - C Helium - He