1. Organization, Names, Trends, and Properties
The Periodic Table
Organization, Names, Trends, and Properties

2. Review What is an isotope?
What value determines the number of protons? Electrons?
What is the mass number and how can we use this to determine the number of neutrons?
Review

3. The three isotopes of chromium are chromium-50, chromium-52, and chromium-53. How many neutrons are in each isotope, given that chromium always has an atomic number of 24?
Isotopes

4. The Periodic Table!!

5. Elements vary widely in their patterns, but in a very orderly way.
Elements in a similar row have similar chemical and physical properties.
Dmitri Mendeleev organized the elements based on their sets of properties.
Periodic Pattern

6. The Periodic Law states that when the elements are arranged according to their atomic numbers, elements with similar properties appear at regular intervals
The Periodic Law

7. Elements in each column have the same number of electrons in their outer most level.
These outer most electrons are known as the valence shell electrons
These valence electrons are the ones that do all the reacting and interacting.
Valence Electrons

8. Valence Electrons

9. A vertical column on the periodic table is known as a group
A horizontal row on the periodic table is known as a period
Elements in the same period have the same number of occupied energy levels.
Elements in the same group tend to react the same (same number of valence electrons)
Arrangement

10. Elements in groups 1, 2 and 13-18 are known as the main-group elements
The electron configurations of the elements in each main group are regular and consistent.
The elements in each group have the same number of valence electrons
Ex: elements in group 2 all have two valence e-’s
ns2, where n is the period number
The main-group elements are sometime referred to as representative elements
Main Group Elements

11. Noble Gases Group 18 elements are known as the noble gases
Octet Rule = 8 outermost electrons (STABLE)
They HAVE their octet achieved already (8 valence electrons)
Soooooo, are they reactive????
It is the full outer shell than lead scientists to believe 8 was nonreactive, not the other way around
Noble Gases

12. Halogens Elements in Group 17 are known as the halogens
The halogens are the MOST reactive group of nonmetal elements because they are soooo close to achieving their octet (they have to STEAL one electron)
React with most metals to form salts
In fact, the name halogen is Greek for “salt maker.”
Halogens

13. Alkaline-Earth Metals
Group 2 elements are called the alkaline-earth metals
Also, HIGHLY reactive
Because they are highly reactive they are usually found as compounds rather than as pure elements.
Slightly less reactive than the alkali metals because they have two electrons to get rid of instead of just one to achieve the octet rule
Alkaline-Earth Metals

14. Alkali Metals Elements in Group 1 are called alkali metals
Name this because they all react with water to make alkaline (basic) solutions
Ex: K reacts vigorously with H2O to yield KOH
Because alkali metals have ________ valence electron(s) they are __________ reactive.
They need to ________________ to obtain their octet.
Alkali Metals

15. Hydrogen is Special Hydrogen is in a class all by itself
It is the MOST COMMON element in the universe
Roughly 3 out of every 4 atoms in the universe is H
Hydrogen has _________ electron(s) but wants _______.
Does not follow the ______________ rule
Hydrogen is Special

16. Metals Most elements are metals
All metals are excellent conductors of electricity
Great conductors of heat
Ductile (can be squeezed into a wire) and malleable (can be pounded into shape)
Alloys are mixtures of elements, giving them a mixture of properties  eliminate bad properties and give the good ones.
Metals

17. Transition Metals are groups 3–12 (we know them as??)
Sometimes called the d-block b/c of their position
DO NOT have the same number of valence electrons
This causes the varying charges
May lose or gain DIFFERENT numbers of electrons depending on who its bonding with (again, explaining the varying charges)
Also good conductors or heat / electricity
Transition Metals

18. f - Block Lanthanides and Actinides
Lanthanides - Shiny metals similar in reactivity to the alkaline-earth metals
Actinides – Nuclei are unstable, making all of them radioactive. The best known actinide is U, or _______________.
f - Block

19. Electron Shielding blocks the outer electrons from the inner nucleus attraction, making them less tightly held.
Electronegativity decreases from right to left and top to bottom.
Atomic radius increase from right to left and top to bottom. (The “F” rule)
Ionization Energy decreases right to left and top to bottom.
Periodic Trends

20. Electronegativity – a measure of the ability of an atom in a chemical compound to attract electrons
Decreases as you move down a group
Decreases
Decreases
Electronegativity

21. Atomic Radius – the overall size of the energy levels surrounding the atom
“F-rule” = Francium is HUGE and Fluorine is TINY
Increases
Increases
Atomic Radii

22. Ionization Energy – the energy required to remove an electron from an atom or ion. (Decreases down and to the left)
Decreases
Decreases
Periodic Trends

23. Average Atomic Mass These are relative atomic masses
Why are the atomic masses of most elements on the periodic table not exact whole numbers?
These are relative atomic masses
Most have isotopes and are a mixture of these differently massed species.
Average Atomic Mass

24. Most Elements are Mixtures of Isotopes
The periodic table reports Average Atomic Mass, a weighted average of the atomic mass of an element’s isotopes.
Example: If I said there was a larger abundance of C-12 than C-13, which value would the average atomic mass be closer to?
Most Elements are Mixtures of Isotopes

25. Calculating Average Atomic Mass
If you know the abundance of each isotope, you can calculate the average atomic mass of an element.
The mass of a Cu-63 atom is amu, and that of a Cu-65 atom is amu. Abundance of Cu-63 is 69.17% and Cu-65 is 30.83%. Find the average atomic mass of Cu.
Calculating Average Atomic Mass

26. Calculate the average atomic mass for gallium if 60
Calculate the average atomic mass for gallium if 60.00% of its atoms have a mass of amu and 40.00% have a mass of amu.
Calculate the average atomic mass of oxygen. Its composition is 99.76% of atoms with a mass of amu, 0.038% with a mass of amu, and 0.20% with a mass of amu.
More Practice

27. Calculate the molar mass for each of the following compounds:
CsI C12H22O11 HC2H3O2
CaHPO4 I2 Mg3(PO4)2
Molar Masses