1. Objective 4.03
Objective 4.03: Explain how the Periodic Table is a model for:
• Classifying elements
• Identifying the properties of elements

2. Mendeleev’s Periodic Table
Mendeleev’s periodic table arranges elements according to the atomic mass
Atomic mass is the number of protons and neutrons
Elements with similar properties are found in the same column
Periodic table—chart that organizes information about all of the known elements according to their properties

3. Today’s Periodic Table
1913, Henry Moseley showed that atomic number was the most important feature because it is what is responsible for chemical properties
Electron configuration determines chemical properties
Today elements are in order of the atomic number
Atomic number—number of protons in the nucleus of an atom

4. Today’s Periodic Table

5. Periodic Table
Chemical family or group is the Vertical column on the periodic table
All have similar properties, numbered 1-18 and from 1A to 8A, all have same number of valence electrons
Groups 1-2(IA-IIA) and 13-18(IIIA-VIIIA) are the main groups
Groups 3-12 are called transition elements
Elements on the left side of the periodic table are metals, except hydrogen
Elements on the right side of the periodic table are nonmetals

6. Today’s Periodic Table

7. Properties of Nonmetals
Properties of Metal
Properties of Nonmetals
Solid at room temperature, except mercury, which is a liquid
Most are gases, except bromine, which is a liquid
Malleable(shaped) and ductile (drawn into wire)
Brittle in solid phase
Have luster (shiny)
Normally dull
Have high thermal and electrical conductivity
Are poor conductors of heat and electricity
Tend to lose electrons in chemical reactions
Tend to gain electrons in chemical reactions
Reactivity describes how likely an element is to form bonds with other elements

8. Group 1 and Hydrogen
Hydrogen is found above Group 1 but doesn’t belong to any group
Placed here because it only has one valence electron. It’s properties are different from the other groups.

9. Alkali Metals Group 1 (Alkali Metals) on periodic table
Most chemically active
One electron in the outer shell
Easily combine with nonmetals
Reactivity of the metal decreases with increasing atomic number
Reactivity increases

10. Alkaline Earth Metals
Group 2 (Alkaline Earth Metal) on the periodic table
Highly reactive but less reactive than group 1
Reactivity of the metal increases with increasing atomic number
Reactivity increases

11. Transition Metals
Group 3 –12 (transition metals) on the periodic table
Generally hard solids with high melting points
Often form colored ions

12. Metalloids Metalloids
Found along the zigzag between the metals and nonmetals on the periodic table
Have properties of both metals and nonmetals

13. Halogens Group 17 (Halogens) on the periodic table
Most reactive of the nonmetals
Reactivity in nonmetals increases as atomic number decreases
Fluorine (F) is the most reactive
Halogens react with alkali metals to form salts
Elements in this family are all states of matter
Fluorine(Fl) and Chlorine—gases
Bromine (Br)—liquid
Iodine (I) and Astatine (At) are solids at room temperature

14. Noble Gases Group 18 (Noble Gases) on periodic table
Least reactive of all elements
Inert—unable to react chemically

15. Periods Periods are the rows
Elements in the same period have the same number of electron orbits(shells)
Atoms are similar sizes
Electronegativity (tendency to attract electrons) increases from left to right

16. Periodic Table http://www.periodictable.com/