1. Ch. 6 The Periodic Table

2. 6.1 Organizing the Elements
Early chemists used properties of elements to sort them into groups
J.W. Dobereiner classified elements into triads with similar properties
Noted that 1 of the three had properties (i.e. mass) in between the other two
Ex: average of the masses of iodine and chlorine is very near the mass of bromine

3. Mendeleev’s Periodic Table
Developed for students
Arranged elements in order of increasing atomic mass*
Periodic repetition of properties
Left blank spaces where no known element fit the mass and properties
Elements later discovered that were predicted by this table

5. Today’s Periodic Table
Arranged in order of increasing atomic number
Periodic Law: when elements are arranged by increasing atomic number, there is a periodic repetition of physical and chemical properties

7. Metals, Nonmetals, and Metalloids
Three broad classes of elements

9. Metals Good conductors of heat and electrical current
Luster/sheen: ability to reflect light
Solid at room temperature (except Mercury)
Ductile: can be drawn into wires
Malleable: can be hammered into sheets without breaking

10. Nonmetals Tend to have properties opposite those of metals
Poor conductors (except carbon)
Brittle solids

11. Metalloids
Properties similar to both metals and nonmetals under different circumstances

13. 6.2 Classifying the Elements
Group 1: alkali metals
Group 2: alkaline earth metals
Elements and : inner transition metals
Groups 3-12: transition metals
Metals in Groups 13-17: other metals
Along zigzag line from Groups 13-17: metalloids
Nonmetals in Groups 14-16: nonmetals
Group 17*: halogens
Group 18: noble gases

14. Grouping by Electron Configuration
Noble Gases: highest energy level is completely full

15. Grouping by Electron Configuration
Representative elements: s or p sublevel of the highest energy level is not filled
Group number (3A, 4A, etc) is the same as the number of electrons in the highest energy level

16. Grouping by Electron Configuration
Transition metals: electrons present in d orbitals
Inner transition metals: electrons present in f orbitals

18. Write the electron configurations of
A) carbon
B) strontium
C) vanadium
List the symbols of all the elements with electron configurations ending in
ns2 np1
ns2np5
nd2
n can be 2, 3, 4, 5, 6, 7 of the highest occupied energy level

19. Electron configuration of
A) carbon: 1s22s22p2
B) strontium: 1s22s22p63s23p64s23d104p65s2
C) vanadium: 1s22s22p63s23p64s23d3
ns2 np1 B, Al, Ga, In, Tl, Uut
ns2np5 F, Cl, Br, I, At, Uus
nd2 Ti, Zr, Hf, Rf

20. 6.3 Periodic Trends Trends in atomic size (atomic radius)
Atoms increase in size from top to bottom within a group
More protons, neutrons, and electrons take up more space, different energy levels, etc.
Atoms decrease in size from left to right across a period
As more protons and electrons are added (electrons in the same energy level) the increasing charge of the nucleus pulls electrons in closer
Shielding effect: if far enough away, charge attraction is ineffective
Atomic radius: ½ the distance between 2 nuclei of two atoms of the same element joined together

21. Ions Ions are formed when a neutral atom gains or loses electrons
Positive ions (cations) are formed when electrons are lost
Negative ions (anions) are formed when electrons are gained

22. Ionization Energy
Ionization energy is the energy required to remove an electron from an atom
The first ionization energy is the energy required to remove the first electron
The second ionization energy is energy to remove a second electron
Ionization energy decreases from top to bottom in a group
Ionization energy increases from left to right across a period
Subsequent ionization energies are greater than the first ionization energy

23. Ion Size Ionic size is different from the neutral atom size
Cations are smaller than the neutral atom
Anions are larger than the neutral atom
Ionic size increases from top to bottom in a group
Ionic size of anions and cations decreases from left to right in a period

24. Ion Size

25. Electronegativity
Electronegativity: ability of an element to attract electrons to itself in a compound
Can be used to predict the type of bond that will form between two elements
Example: in a water molecule, oxygen is more electronegative
The electrons in the compound are drawn closer to (or held more tightly by) the oxygen atom than the hydrogen atoms

26. Electronegativity Trends
Electronegativity values decrease from top to bottom in a group
Electronegativity values increase from left to right across a period
Noble gases do not have electronegativity values

27. What Ion does it form? Li Mg Rb Ca K P Cl Be F O N I Al Br S

28. What Ion does it form? Li+1 Mg+2 Rb+1 Ca+2 K+1 P-3 Cl-1 Be+2 F-1 O-2
Al+3
Br-1
S-2

29. Ch. 6 Assessment Questions