1. Periods, groups, and trends
The Periodic Table
Periods, groups, and trends

2. The Bohr Model
After Rutherford’s model of the atom, Neils Bohr created our modern atomic model
He suggested that the electrons of an element are arranged in energy levels or “energy shells”
Using this model helps us understand the periodic table of elements

4. What is The Periodic Table of Elements?
An arrangement of the elements

5. Periodic Law
“When the elements are arranged according to their atomic numbers, elements with similar properties appear at regular intervals”
When elements are arranged by their atomic numbers, groups of elements begin to have similar characteristics

6. Organization of the Periodic Table
Elements in each column of the periodic table have the same number of electrons in their outer shell
Called “valence electrons”
Elements with the same number of valence electrons react in similar ways

7. Periods
A horizontal row on the periodic table of elements is called a period

8. Groups A vertical column of the periodic table is called a group
Elements in a group share similar chemical properties

9. Main Group Elements
Elements in groups 1,2, and are known as main group elements
Electron configurations of each element are regular and consistent
Main group elements include:
Alkali Metals
Alkaline Earth Metals
Halogens
Noble Gases

10. Alkali Metals – Group 1

11. Alkali Metals – Group 1 They are metals that react with water
They are very reactive
Never found in nature as “pure elements” but are found as compounds
Lithium, Sodium, Potassium, Rubidium, Cesium, and Francium

12. Alkaline Earth Metals – Group 2

13. Alkaline Earth Metals – Group 2
Slightly less reactive than Alkali Metals
Have 2 valence electrons

14. Halogens – Group 17

15. Halogens– Group 17 The most reactive group of the non metal elements
They have 8 valence electrons
React with most metals to produce salts
Sodium and Chlorine – Table Salt

16. Noble Gases – Group 18

17. Noble Gases – Group 18 Group 18 elements are called Noble Gases
Have a very low reactivity

18. Hydrogen The most common element in the universe
It only has one proton and one electron so it is unlike any other element
Reacts with many other elements

19. Transition Metals
These occupy the center of the periodic table

20. Transition Metals cont.
Extremely unreactive
Some almost never form compounds with other elements

21. Metals All Metals are excellent conductors of electricity
Most often distinguishes metals from non-metals
Can be brittle or malleable

22. Metalloids
Found on the table between metals and non metals

23. Metalloids All metalloids are solids at room temperature
Have some characteristics of metals and have some characteristics of non-metals

24. Non-Metals Many non-metals are gases at room temperature
Poor conductor of heat and electricity
Found on the right side of the periodic table

25. Periodic Trends
The arrangement of the periodic table reveals trends in the properties of the elements
A trend is a predictable change or characteristic
Understanding a trend among elements in a group or period enables you to make predictions about their behavior

26. Ionization Energy
Ionization energy is the energy required to remove an electron from an atom

27. Ionization Energy Cont.
Ionization energy decreases as you move down a group

28. Ionization Energy cont.
Ionization energy increases as you move from left to right across a period

29. Melting Point Metals generally posses a high melting point
Most nonmetals possess low melting points

30. Electronegativity
Refers to how strongly each atom attracts other electrons
An atom with higher electronegativity will pull on the electrons more strongly than another atom will
Electronegativity decreases as you move down a group
Electronegativity increases from left to right across a period