1. Day 2 - The Atom, the periodic table, and you :
And let’s not forget those wacky funsters the orbitals 

2. The Atom
The word ATOM comes from the Greek atomos – which means ‘indivisible’ and started to be used extensively in the 19th century as a term to describe the smallest form of any given element.
It wasn’t until the early part of the 20th century that it was discovered that atoms were composed of smaller ‘particles’. These particles are:
* Electrons (negatively charged - ) written as e-
* Protons (positively charged + ) written as P+
* Neutrons (zero charge 0 ) written as N0
** Protons and Neutrons make up the NUCLEUS of an atom.
• Electrons are much, much smaller than Protons. A proton is approx times more massive but we are not sure of the actual size of an electron – we only know its mass ( × 10-31 kilograms) The mass of a proton is × 10-27 kilograms.

3. Electrons are very energetic
Electrons are very energetic. The speed of a hydrogen electron has been measured to be 2.2x106 m/s. This is approx. 0.7% of the speed of light.
If the proton of a Hydrogen (H) atom was the size of a basketball, its lone electron would be the size of a golf ball and would be ~8 km away.

4. The Periodic table
The Periodic Table we now use is a collection, in order, of the 118 elements that we know of (103 are naturally occurring). The basic framework was developed by Dimitri Mendeleev. The table is arranged by Atomic Number, Electron Configuration, and Recurring Chemical Properties.

5. The Groups that we will be referring to the most:
The table is arranged in vertical columns called Groups and in horizontal rows called Periods.
The Groups that we will be referring to the most:
Group 1 (H, Li, Na, K, Rb, Cs, Fr) the Alkali Metals
Group 2 (Be, Mg, Ca, Sr, Ba, Ra) the Alkali Earth Metals
Group 17 (F, Cl, Br, I, At, Ts) the Halogens
Group 18 (He, Ne, Ar, Kr, Xe, Ra, Og) the Noble Gases
NOTE: Ts (Tennessine) is artificail, as is Og (Oganesson).
When elements combine, it is the individual atoms of the element that combine. Since atoms are the smallest complete unit of an element, atoms combine in a definite proportion. (You can’t half an atom!!)
Atoms combine as a complete unit, so when atoms of one element combine with atoms of another element they combine in a WHOLE NUMBER RATIO.
Example: H2 + O2 = 2 H2O (Those numbers in front mean MOLAR RATIO – 2 moles of Hydrogen gas combine with 1 mole of Oxygen gas.

6. Patterns and trends within the periodic table.
Major periodic trends include: electronegativity, ionization energy, electron affinity, atomic radius, melting point, and metallic character.
Periodic trends, arising from the arrangement of the periodic table, provide chemists with an invaluable tool to quickly predict an element's properties.
Electronegativity - Electronegativity measures an atom's tendency to attract and form bonds with electrons.
This property exists due to the electronic configuration of atoms. Most atoms follow the octet rule (having the valence, or outer, shell comprise of 8 electrons).
Because elements on the left side of the periodic table have less than a half-full valence shell, the energy required to gain electrons is significantly higher compared with the energy required to lose electrons.
As a result, the elements on the left side of the periodic table generally lose electrons when forming bonds.
Electronegativity increases as we move left to right across periods.
Electronegativity decreases as we move from top to bottom of a group.
These rules DO NOT apply to Noble Gases, Actinides ( Th to Lr ) and Lanthanides ( Ce to Lu).

7. Elements on the Left side of the table have a tendency to LOSE electrons when forming bounds.
Elements on the Right side of the table have a tendency to GAIN electrons.
The nature of electronegativity is effectively described thus: the more inclined an atom is to gain electrons, the more likely that atom will pull electrons toward itself.

8. Ionization Energy Trends
Ionization energy is the energy required to remove an electron from the outer shell of an atom in its gaseous state.
Ionization energy tends to decrease from the top of a group to the bottom of that group (this explains why Cesium (Cs) is more reactive than Lithium (Li).
It also tends to increase as you move left to right across a period (more energy is required to remove an electron from Fluorine (F) than from Lithium (Li) ). This is because the electrons are closer to the nucleus moving left to right)

9. Trends in ionic size Na+ + Cl-  NaCl
When an element loses an electron(s) it becomes an ion and has a positive charge. It is called a CATION.
When an element gains an electron(s) it becomes an ion with a negative charge. It is called an ANION.
As an example, all elements in Group 1 have a 1+ charge in ionic form. Elements in Group 17 have a 1- charge in ionic form.
Example: Sodium combines with Chlorine to form Sodium Chloride
Na+ + Cl-  NaCl
The charges on the cation and anion cancel each other out to form a stable molecule with a neutral (0) charge.
Elements from Group 1 to Group 12 tend to form CATIONS that decrease in side as you move left to right.
Elements from Group 13 to Group 17 tend to form ANIONS that decrease in size as you move left to right.
NOBLE GASES DO NOT FORM IONS EXCEPT UNDER EXTRAORDINARY CONDITIONS

10. Atomic NUMBERS, ATOMIC MASS, and ORBITALS
Each element on the Periodic Table has a specific NUMBER and a specific MASS.
The ATOMIC NUMBER is the number of protons in the nucleus of an atom of the element.
Example: Hydrogen (H) has an atomic number of 1 and has 1 proton Oxygen (O) has an atomic number of 8 and has 8 protons.
The ATOMIC MASS is the number of protons and the number of neutrons in the nucleus of an atom of the element.
Hydrogen (H) has an atomic mass of and Oxygen (O) has an atomic mass of ** We round these values to be 1.00 and respectively.
The ATOMIC MASS can be measured both in Atomic Mass Units (AMU) and Grams per Mole (g/mole). The numerical value is the same but the units will differ. EXAMPLE: Oxygen has an atomic mass of 16 amu AND it can be written as 16 g/mole.

11. Orbitals
Electrons are arranged around the nucleus of the atom in discrete shells or orbitals.
Each of these orbitals can only hold a specific number of electrons and are arranged in this order: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 (this is the orbital configuration for the Noble gas Krypton (Kr) )
s orbitals can hold a maximum of 2 electrons
p orbitals can hold a maximum of 6 electrons
d orbitals can hold a maximum of 10 electrons.
As an example Hydrogen (H) is 1s1, Helium (He) is 1s2, Lithium (Li) is 1s2 2s1
If you are given the orbital (electron) configuration, you should be able to determine the element.
Example 1s2 2s2 2p6 3s1 is Sodium (Na)
1s2 2s2 2p6 3s2 3p4 is Sulfur (S)
HINT HINT HINT !!! Add up the electrons and then find the element that matches that number…

12. Assignment # 2 Use your periodic table to answer the following
Write out the orbital (electron) configuration for each of the following: (5)
Mg (Magnesium)
C (Carbon)
Ca (Calcium)
O (Oxygen)
Ne (Neon)
Name the element, and its symbol, given the orbital (electron) configuration. (5)
1s2 2s2 2p6 3s2 3p6 4s1
1s2 2s2 2p3
1s2 2s2 2p6 3s2 3p5
1s1
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6