1. The Periodic Table and Periodic Law
Chemistry Lesson 6 -
The Periodic Table and Periodic Law
Ms. Eline
Bordentown Regional High School

2. The Periodic Table-The History of the Periodic Table 6.1
CONTRIBUTIONS TO THE PERIODIC TABLE
John Newlands ( ) arranged elements by increasing mass
noticed the repetition of properties of every eighth element
created the law of octaves
Lothar Meyer ( ) demonstrated a connection between atomic mass and elements’
propereties.
arranged the elements in order of increasing atomic mass.
Demetri Mendeleev( ) demonstrated a connection between atomic mass and elements’
properties.
predicted the existence and properties of undiscovered elements.
Henry Mosley( ) discovered that atoms contain a unique number of protons called the
atomic number
arranged elements in order of increasing atomic number which resulted
in a periodic pattern of properties.

3. The Periodic Table-The History of the Periodic Table 6.1
The Periodic Table brought order to seemingly unrelated facts and became a significant tool for all scientists!
The Modern Periodic Table- consists of boxes, each containing an element name, symbol, atomic number, and atomic mass.

4. The Periodic Table-The History of the Periodic Table 6.1
The Periodic Table brought order to seemingly unrelated facts and became a significant tool for all scientists!
Periodic Law- There is a periodic repetition of chemical and physical properties of the elements when arranged by periodic number

5. The Periodic Table-The History of the Periodic Table 6.1

6. The Periodic Table -The History of the Periodic Table 6.1
There are a total of 7 periods. Each group is numbered 1 through 18. The elements in Groups 1,2 and 13 to 18 possess a wide range of chemical and physical properties. They are the main group or REPRESENTATIVE ELEMENTS. Groups 3 to 12 are referred to as the transition metals. All elements are classified as metals, nonmetals or metalloids.
Looking at Boron(B) in column 13 you see a heavy stairstep line that zigzags down to Astatine(At) at the bottom of group 17. This is the visual divider between the metals and the nonmetals.
Metals- In our table are blue- are generally shiny when smooth and clean, solid at room temperature and good conductors of heat and electricity. Most are malleable and ductile. Most representative and all transition elements are metals.
Nonmetals- In our table are yellow-Nonmetals are elements that are generally gases or brittle, dull-looking solids. They are poor conductors of heat and electricity.
Metalloids –in our table are green- Metalloids have physical can chemical properties of both metals and nonmetals/ Silicon(Si) and Germanium(Ge) are 2 important metalloids used extensively in computer chips and solar cells.

7. Periodic Table-The History of the Periodic Table 6.1
Alkali metals- Except for hydrogen all of the elements on the left side of the table are metals. The group I elements are known as the alkali metals. Because they are so reactive alkali metals usually exist as compound with other elements. Example - NaCl
Alkaline Earth Metals- are also highly reactive. Calcium and Magnesium two important minerals for your health are examples of alkaline earth metals. Magnesium is solid and relatively light.
Transition Metals- Transition and Inner Transition Metals:Lanthanide and Actinide series. Elements from the inner lanthanide series are used extensively as phospors. Titanium is used to make frames for bicycles and eyeglasses.

8. The Periodic Table-Classification of Elements 6.2
Elements in group 1 have 1 valence electron. Group 2 has 2 valence electrons. Groups have ten less than their group number.
Number of Valence Electrons by Group

9. Periodic Table-Classification of Elements 6.2
The periodic table has columns and rows of varying sizes. The reason behind the table’s odd shape becomes clear if it is divided into sections representing the atom’s energy sublevel being filled with valence electrons. There are 4 different energy sublevels (s, p, d and f)

10. The Periodic Table-Classification of Elements 6.2
s-Block elements – Groups 1 and 2 and the element helium.
Group 1 - s Group 2 - s2
p-Block elements – Groups 13 through 18 and the element with filled or partially filled p orbitals. When both the s and p orbitals corresponding to the period’s principal energy level are completely filled this is an unusually stable atomic structure. Together the s and p orbitals comprise the representative elements.
d-Block elements – Contains the transition metals and is the largest of the blocks. Mostly consists of a filled outermost s level of energy level n and filled or partially filled d orbitals of n-1.
Example Scandium (Sc) the first d-block element has an electron configuration of [Ar]4s23d1 and Titanium(Ti) the next is [Ar]4s23d2. According to aufbau the 4s has a lower energy than 3d.
f-Block elements - Contains the inner transition metals. Its elements are characterized by a filled or partially filled outermost s orbital and filled or partially filled 4f and 5f orbitals. The electrons of an f level do not fill their orbitals in a predictable manner. Because there are 7 f orbitals the f-block spans 14 columns of the periodic table.

11. Atomic Radius The Periodic Table-Periodic Trends 6.3
The outer limit of an electron cloud is defined as the spherical surface within which there is a 90% probability of finding an electron. Atomic size is defined by how closely an atom lies to a neighboring atom. For Metals the atomic radius is defined a half the distance between adjacent nuclei in a crystal of that element. For elements that commonly occur as molecules such as the nonmetals the atomic radius is half the distance between nuclei of the 2 atoms.
General Trend- Atomic radii generally decrease from left to right in a period and generally increase as you move down a group.

12. Ionic Radius The Periodic Table-Periodic Trends 6.3
An ion is an atom or a bonded group of atoms that has a positive or negative charge.
When atoms lose electrons and form positively charged ions, they always become smaller. The loss of a valence electron can leave a completely empty outer orbital which results in a smaller radius. When atoms gain electrons they become larger.

13. The Periodic Table-Periodic Trends 6.3
Ionic Radius

14. Ionization Energy The Periodic Table-Periodic Trends 6.3
First Ionization Energy -To form a positive ion, an electron must be removed from a neutral atom. This requires energy, the Ionization energy. For example, the energy required to remove the first outermost electron from a an atom is called the first ionization energy. The first ionization energy of gaseous lithium equals 8.64 x Joules. The loss of the electron results in the formation of the Li+ ion.Think of ionization energy as how strong an atom’s nucleus holds onto its valence electrons.
General Trend- first ionization energies generally increase as you move from left to right across a period. First ionization energies tends to generally decrease as you move down a group.

15. Ionization Energy The Periodic Table-Periodic Trends 6.3
Removing more than one electron- after removing the first electron from an atom it is possible to remove additional electrons i.e. the second ionization energy, the third etc. The energy for each successive ionization always increases

16. Electronegativity The Periodic Table-Periodic Trends 6.3
The relative ability of an atom to attract electrons in a chemical bond. The units are arbitrary units called Paulings after Linus Pauling. Fluorine is the most electronegative with a value of 3.98 and cesium and francium are the least electronegative with values of 0.79 and 0.70, respectively.

17. Electron Affinity The Periodic Table-Periodic Trends 6.3
Electron Affinity is a measure of the tendency of an atom to accept an electron. This value is measured whereas electronegativity is assigned.

18. The Periodic Table-Periodic Trends 6.3
Rules for determining Oxidation Numbers
Rules for Determining Oxidation Numbers
Example
nelement
1. The oxidation number of an atom of an uncombined element is zero.
Na,O2, Cl2, H2
2. The oxidation number of a monoatomic ion is equal to the charge of the ion.
Ca+
Br- +2 -1
3. The oxidation number of the more electronegative atom in a molecule of a complex ion is the same as the charge would have if it were and ion.
N in NH3
O in NO -3 -2
4. The oxidation number of the most electronegative element, fluorine, is always -1 when it is bonded to another element.
F in LiF
5. The oxidation number of oxygen in compounds is always -2 except in peroxide(H2O2) where it is -1. When it is bonded to fluorine, the only element more electronegative than oxygen, the oxidation number is positive.
O in NO2
O in H2O2
6. The oxidation number of hydrogen in most of its compounds is +1, except in metal hydrides, the oxidation number is -1
H in NaH
7. The oxidation number of group 1 and 2 metals and aluminum are positive and equal to their number of valence electrons. K Ca Al +1 +3
8. The sum of the oxidation numbers in a neutral compound is zero.
CaBr2
(+2)+2(-1)=0
9. The sum of the oxidation numbers of the atoms in a polyatomic ion is equal to the charge of the ion.
SO32-
(+4) +3(-2)=

19. Elements of the Body-Percent by Mass
OXYGEN
In the Adult human body, there are more than 14 billion, billion or 1.4 x 1013 oxygen atoms.
Without oxygen in your body for 2 minutes the human body would die.
CARBON
Carbon can form strong bonds with itself and other elements. Carbon forms the long chained backbones of organic molecules such as carbohydrates, proteins and lipids. The DNA molecule that determines your physical features relies on the versatility of carbon and other organic molecules that your body needs for energy.

20. Hydrogen
There are more hydrogen atoms in the body than atoms of all the other elements combined, although hydrogen represents only 10% of the composition by mass because of its significantly lower mass.
Nitrogen
As the figure to the right illustrates, the human body is composed of a large percentage of muscle. For men, the average muscle mass is between 38 percent and 54 percent, while for women the range is between 28 percent and 39 percent. Nitrogen is a critical element for any proteins.

21. Other elements in the body- The remaining elements make up 2% of the Mass of the human body: Sulfur, Phosphorus, Calcium, Magnesium, Potassium, Sodium