1. The Modern Periodic Table

2. Mendeleev and Mosley
Mendeleev’s periodic table was ordered by increasing atomic mass:
Did not work perfectly – some elements were out of order so they would fit in a family that had similar properties.
Modern periodic table is ordered by increasing atomic number:
Henry Moseley: scientist that determined an element’s atomic number (the number of protons in an atom).
Hydrogen Atomic Number is 1, therefore it has 1 proton in the nucleus
Potassium Atomic Number is 19, therefore it has 19 protons in the nucleus
Radon Atomic Number is 86, therefore it has 86 protons in the nucleus
When elements are arranged according to increasing atomic number, the elements fit perfectly in order from

3. The Modern Periodic Table
The modern periodic table consists of:
Groups (1-18): A vertical column of elements; also called a family
Each group has similar physical and chemical properties
Periods (1-7): A horizontal row of elements.
Each row identifies energy level and shell levels that Bohr had predicted.
group: a vertical column of elements in the periodic table; also called a family
period: a horizontal row of elements in the periodic table

4. The Modern Periodic Table
Zig – Zag Line
Group
Period

5. Discussion Questions manganese magnesium arsenic astatine
Give the symbol, atomic number, and number of protons for each of the following elements:
manganese
magnesium
arsenic
astatine

6. Elements are classified as metals, non-metals, or semi-metals
Three broad categories of elements shown on the periodic table:
Metals
Non-metals
Semi-metals
Elements of Groups 1, 2, and 13 to 18 are called main-group elements
Elements in Groups 3 to 12 are called transition elements

7. Metals Property Characteristics Lustre Shiny Malleability
Malleable (can be formed or shaped)
Ductility
Ductile (can be stretched into wire)
Conductivity
Good conductors of heat and electricity
State
Solid at room temperature (except mercury, which is liquid at room temp)
Density
Usually denser than non-metals
Reactivity
Active metals react with acid, very active metals react with water
Boiling Point/Melting Point
Usually have a high boiling point or melting point
metal: typically, an element that is hard, shiny, malleable, ductile, and that conducts electricity and heat; found to the left of the zigzag line on the periodic table

8. Metals: Alkali Metal Alkali metals:
Found in Group 1 (all elements, except hydrogen)
Shiny and soft
Highly reactive with water and oxygen (often stored in a non-reactive liquid such as oil)

9. Metals: Alkaline-Earth Metals
Found in Group 2
Shiny and soft (but not as soft as alkali metals)
Highly reactive (but not as reactive as alkali metals)
Magnesium (left) burns easily in air when ignited.

10. Non-metals Property Characteristics Lustre Dull in appearance
Malleability
Not malleable - likely to be brittle or shatter when struck
Ductility
Not ductile – cannot be stretched into wire
Conductivity
Poor conductors of heat and electricity
State
Often a gas at room temperature (except mercury, which is liquid at room temp)
Density
Usually have low density
Reactivity
Active metals react with acid, very active metals react with water
Boiling Point/Melting Point
Usually have a low boiling point and melting point.
non-metal: typically, an element that is not shiny, malleable, or ductile, and is a poor conductor of electric current and heat; found to the right of the zigzag line on the periodic table

11. Non-metals: Hydrogen Hydrogen:
Usually on the left side of the periodic table
Lightest element
Colourless, odourless, tasteless
Highly flammable
Makes up over 90% of atoms in the universe
On Earth: Most hydrogen is found combined with oxygen as water

12. Non-metals: Halogens Halogens: Found in Group 17
Highly reactive (therefore usually found in nature as part of compounds)

13. Non-metals: Noble Gases
Found in Group 18
Odourless, colourless gases
Least reactive of all of the elements
Helium and neon never form compounds.
Other noble gases form compounds with great difficulty.

14. Semi-Metals Semi-metals: Also known as metalloids
Found in the green boxes in a staircase shape
Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium, Polonium and Astatine.
Have physical and chemical properties of both metals and non-metals
Shiny (like metals)
Brittle and not ductile (like non-metals)
Poor conductors of heat and electricity (like non-metals)
semi-metal: an element that shares some properties with metals and some properties with non-metals

15. Semi-metals: Silicon Silicon:
Second-most abundant element in Earth’s crust (after oxygen)
Used in many electronic devices (computers, smartphones)
Used to make silicone (material used in cookware, contact lenses, prosthetics)

16. Transition Metals Groups 3 – 12 are the transition metals.
These metals have a moderate range of reactivity and a wide range of properties.
In general they are shying and good conductors of heat and electricity.
They also have higher densities and melting points than groups 1 & 2.

17. ATOMIC SIZE
Atomic size decreases moving left to right across a period.
Elements have increasing numbers of electrons across a period.
Number of valence shells stay the same across the period, but the number of protons in the nucleus increases.
As such the protons pull the electrons closer to the nucleus and making the radius smaller.
As you move down the families (each group) the atomic radius of the atom increases, this is because there are more electron shells, and that makes the atom larger.

18. ATOMIC SIZE

19. Periodic Trends/Patterns
1) Elements are arranged by atomic number – this number identifies how many protons and electrons are in the atom.
2) They are arranged into column’s called groups or “families.” These families have similar physical and chemical characteristics.
3) The rows are called periods and they identify the energy level for the elements in that row.
4) The periodic table is divided into metals, semi-metals, and non-metals. The zig-zag line helps us understand where this divide is.
5) Elements in groups 1, 2, and 17 are quite reactive. Elements in group 18, the noble gasses, are very stable.
6) We can use the atomic mass, subtract it from the atomic number, and we can solve for how many neutrons are in the elements.
7) The ion charge will tell us how many electrons an element in ionic form will have.
8) Atomic size decreases across the period but increases down the group.
9) Each period adds one more electron shell (a new energy level). Period 1 has one electron shell, period 2 has two electrons shells and so on. (Will discuss in more detail later)

20. Assignment Page 192 Questions 9-11, 13.
Page 217 Questions 1 – 5, 6-15 and,
Worksheet Questions