1. THE PERIODIC TABLE (Chapter 6)

2. Organizing the Elements
Few elements, including copper, silver, and gold, have been known for thousands of years
There were only 13 elements identified by the year 1700
Chemists began to use scientific methods to search for elements, the rate of discovery increased
In one decade (1765–1775), chemists discovered five new elements

3. J. W. Dobereiner, published a classification system
Early chemists used the properties of elements to sort them into groups
J. W. Dobereiner, published a classification system
The known elements were grouped into triads
A triad is a set of three elements with similar properties

4. Mendeleev arranged elements with…
Mendeleev arranged elements with…. similar properties in the same row (organized by atomic mass)

5. Mendeleev placed tellurium before iodine in his periodic table
The problem wasn’t with the atomic masses but with using atomic mass to organize the periodic table
Mendeleev placed tellurium before iodine in his periodic table

6. Today’s Periodic Table
In the modern periodic table, elements are arranged in order of increasing atomic number (number of protons in the nucleus)

7. Properties of the elements within a period change as you move across a period from left to right.
Pattern of properties within a period repeats as you move from one period to the next
Elements that have similar chemical and physical properties end up in the same column in the periodic table

8. Metals, Nonmetals, Metalloids

9. Metals
Good conductors of heat & electrical current
Luster (shiny)
Solid at room temperature except Mercury (Hg)
Malleable & ductile
Nonmetals
Poor conductors of heat & electrical current
Most are gases at room temperature (main components of air—nitrogen and oxygen)
Few are solids (sulfur and phosphorus) & Bromine (Br) is a liquid
Brittle
Metalloids
Properties similar to those of metals & nonmetals (depending on conditions)
Silicon is used in computer chips

11. What information can be learned about the elements on the periodic table?
Drivers license tell us information…..Name, eye color, height, weight, address, date of birth (unique to each individual)

12. What Information can we get about an element?

13. SOLIDS, LIQUIDS, GASES Solids chemical symbol is in black
Gases chemical symbol is in red
Liquids chemical symbol is in blue
**Could be three different colors on a different periodic table (these colors are in reference to the ones in your textbook)

14. Groups/Families of the Periodic Table
The elements in Group 1 are called alkali metals
The elements in Group 2 are called alkaline earth metals

15. The nonmetals of Group 7 are called halogens
The nonmetals of Group 8 are called Noble Gases

16. Transition Elements Transition metals
Displayed in the main body of the periodic table
Copper, silver, gold, and iron are transition metals
Characterized by the presence of electrons in d orbitals
Inner transition metals
Appear below the main body of the periodic table
Characterized by the presence of electrons in f orbitals(4f & 5f)

17. Representative Elements
Elements in Groups 1-2 and 3-7 (s and p blocks) are often referred to as representative elements
They display a wide range of physical and chemical properties.

18. Valence Electrons
The number of outer or “valence” electrons in an atom affects the way an atom bonds
All atoms want to acquire an octet (8 electrons in the outer shell)… this is why atoms bond together!
Atoms gain or lose electrons (forming ions) to obtain the octet

19. There are different ways to determine the number of outer shell VALENCE electrons in a given element
Electron configuration
Bohr Diagrams
Group Number (Representative elements)

21. Electron Configuration

22. Bohr Diagrams

23. DETERMINING VALENCE ELECTRONS

24. For any representative element its group number equals the number of valance electrons (electrons in the highest occupied energy level)

25. IONS
An ion is an atom or group of atoms that has a positive or negative charge
Atoms become ions when electrons are lost or gained
Atoms can become cations or anions

26. Cation (Positively charged ion)
More positively charged protons than negatively charged electrons, the ion has a net positive charge
The charge for a cation is written as a number (number of electrons lost) followed by a plus sign
Metals tend to form cations

27. Anion (Negatively Charged ion)
More negatively charged electrons than positively charged protons, the ion has a net negative charge
The charge for an anion is written as a number (number of electrons gained) followed by a minus sign
Nonmetals tend to form anions

29. PERIODIC TRENDS
Chapter 6.3

30. Atomic Size The size is expressed as an atomic radius
The atomic radius is the distance from the nucleus to the outermost energy level

31. In general, atomic size increases from top to bottom within a group, and decreases from left to right across a period

32. Rubidium, Gallium, Potassium
Practice Question....
1. Which of the following has the smallest atomic radius?
Rb, Cs, O
2. Order the following atoms in increasing atomic radius (smallest to largest)
Rubidium, Gallium, Potassium

33. Ionization Energy
Ionization energy is the energy required to remove an electron from an atom
Ionization energy tends to decrease from top to bottom within a group and increase from left to right across a period

34. Practice Question...
1. Which of the following elements has the lowest ionization energy
Sodium, Lithium, Potassium, Fluorine
2. List the following elements in increasing ionization energy
Chlorine, Lithium, Oxygen, Beryllium