1. The Simplest Matter Chapter 1 Section 2

2. The Elements All of the different materials have one thing in common. They are made up of even simpler materials. All of the different materials have one thing in common. They are made up of even simpler materials. Lead 82 Pb 207.19 Silicon 14 Si 28.09 Beryllium 4 Be 9.01

3. One Kind of Atom An element is matter made of only one kind of atom. 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. At least 115 elements are known and about 90 of them occur naturally on Earth. These elements make up gases in the air, minerals in rocks, and liquids such as water. These elements make up gases in the air, minerals in rocks, and liquids such as water.

4. One Kind of Atom Examples of naturally occurring elements include the oxygen and nitrogen in the air we breathe, and metals gold, silver, and iron. Examples of naturally occurring elements include the oxygen and nitrogen in the air we breathe, and metals gold, silver, and iron. Other elements are known as synthetic elements. They have been made in nuclear reactions by scientists with machines called particle accelerators. Other elements are known as synthetic elements. They have been made in nuclear reactions by scientists with machines called particle accelerators. Some synthetic elements have important uses in medical testing. Some synthetic elements have important uses in medical testing.

5. The Periodic Table

6. Periodic Table Each element is represented by a chemical symbol that contains 1-3 letters. Each element is represented by a chemical symbol that contains 1-3 letters. The symbols are a form of chemical shorthand that chemists use to save time and space- on the periodic table as well as in written formulas. The symbols are a form of chemical shorthand that chemists use to save time and space- on the periodic table as well as in written formulas. The elements are organized on the periodic table by their properties. The elements are organized on the periodic table by their properties.

7. The Periodic Table There are rows and columns that represent relationships between the elements. There are rows and columns that represent relationships between the elements. The rows in the table are called periods. The rows in the table are called periods. The elements in a row have the same number of energy levels. The elements in a row have the same number of energy levels. The columns are called groups. The columns are called groups. The elements in a column have similar properties related to their structure. The elements in a column have similar properties related to their structure.

8. Periodic Table

9. Number of Protons and Neutrons Cl is the symbol for Chlorine. Cl is the symbol for Chlorine. The top number is the element’s atomic number. 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. It tells you the number of protons in the nucleus of each atom of that element.

10. Isotopes Although the number of protons changes from element to element, every atom of the same element has the same number of protons. Although the number of protons changes from element to element, every atom of the same element has the same number of protons. However, the number of neutrons can vary even for one element. However, the number of neutrons can vary even for one element. Isotopes are atoms of the same element that have different numbers of neutrons. Isotopes are atoms of the same element that have different numbers of neutrons.

11. Isotopes You can tell someone exactly which isotope you are referring to by using its mass number. You can tell someone exactly which isotope you are referring to by using its mass number. An atoms atomic mass is the number of protons plus the number of neutrons it contains. An atoms atomic mass is the number of protons plus the number of neutrons it contains. The numbers 35 and 37,which were used to refer to Cl, are mass numbers. The numbers 35 and 37,which were used to refer to Cl, are mass numbers.

12. Atomic Mass The atomic mass is the weighted average mass of the isotope of an element. The atomic mass is the weighted average mass of the isotope of an element. The atomic mass is the number found below the element symbol. The atomic mass is the number found below the element symbol. The unit that scientist use for atomic mass is called the atomic mass unit, which is given the symbol u. The unit that scientist use for atomic mass is called the atomic mass unit, which is given the symbol u. The calculation of atomic mass takes into account the different isotopes of the element. The calculation of atomic mass takes into account the different isotopes of the element.

13. Classification of Elements Elements fall into 3 general categories: metals, nonmetals, and metalloids. Elements fall into 3 general categories: metals, nonmetals, and metalloids. Metals generally have a shiny or metallic luster and are good conductors of heat and electricity. 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. All metals, except Mercury are solids at room temperature.

14. Metals Metals are malleable meaning; they can be bent and pounded into various shapes. Metals are malleable meaning; they can be bent and pounded into various shapes. Metals are also ductile meaning; they can be drawn into wires without breaking. Metals are also ductile meaning; they can be drawn into wires without breaking. If you look at the periodic table, you can see that most the elements are metals. If you look at the periodic table, you can see that most the elements are metals.

15. Nonmetals Nonmetals are elements that are usually dull in appearance. Nonmetals are elements that are usually dull in appearance. Most are poor conductors of heat and electricity. Most are poor conductors of heat and electricity. Many are gases at room temperature. Many are gases at room temperature. The solid nonmetals are generally brittle; meaning they cannot change shape easily without breaking. The solid nonmetals are generally brittle; meaning they cannot change shape easily without breaking.

16. Nonmetals The nonmetals are essential to the chemicals of life. They make up more that 97 percent of our bodies. Some examples are Carbon, Oxygen, Hydrogen, Calcium, Nitrogen. The nonmetals are essential to the chemicals of life. They make up more that 97 percent of our bodies. Some examples are Carbon, Oxygen, Hydrogen, Calcium, Nitrogen. Except for the Hydrogen, the nonmetals are found on the right side of the periodic table. Except for the Hydrogen, the nonmetals are found on the right side of the periodic table.

17. Metalloids Metalloids are elements that have characteristics of metals/nonmetals. Metalloids are elements that have characteristics of metals/nonmetals. On the periodic table, metalloids are found between the metals and nonmetals. On the periodic table, metalloids are found between the metals and nonmetals. All metalloids are solids at room temperature. All metalloids are solids at room temperature. Some metalloids are shiny and many are conductors, but they are not as good at conducting heat and electricity as metals are. Some metalloids are shiny and many are conductors, but they are not as good at conducting heat and electricity as metals are. Some metalloids, such as silicon, are used to make the electronic circuits in computers, televisions, and other electronic devices. Some metalloids, such as silicon, are used to make the electronic circuits in computers, televisions, and other electronic devices.