Lesson 11: Trends on the Periodic Table
> elements close to each other on periodic table display similar characteristics
> 7 important periodic trends:
1. Reactivity
2. Ion Charge
3. Melting Point
4. Atomic Radius
5. Ionization Energy
6. Electronegativity
7. Density *
Reactivity
> metals and non-metals show different trends
> most reactive metal is Francium; most reactive non-metal is Fluorine
Ion Charge
> elements' ion charges depend on their group (column)
Melting Point
> elements of the highest melting point in center of table
> noble gases have the lowest melting points
> starting from left to right, melting point increases (until middle of table)
Atomic Radius
> radius decrease to the up and the right
> Helium has the smallest atomic radius
> Francium has the largest atomic radius
Ionization Energy
> the energy needed to completely remove an electron from an atom
> increases going up and to the right
> all noble gases have HIGH ionization energy
> Helium has highest ionization energy
> Francium has lowest ionization energy
> OPPOSITE trend from atomic radius
Electro Negativity
> refers to how much atoms want to gain electrons
> same trend as ionization energy
And in more recent news...
THIS JUST IN: NEW GROUND-BREAKING
PHYSICS DISCOVERY
~ kim nipp
LESSON 10
Isotopes & Atoms
Atomic Number
- Number of protons
Atomic mass - Atomic # = # of neutrons
(p + n) (p) (n)
- Isotopes have the same atomic number but a different mass
| ISOTOPE | MASS # | ATOMIC # | # PROTONS | # NEUTRONS |
| Lawrencium- 257 | 257 | 103 | 103 | 154 |
| Uranium-238 | 238 | 92 | 92 | 146 |
| Thorium-232 | 232 | 90 | 90 | 142 |
| Hydrogen-1 | 1 | 1 | 1 | 0 |
Manganese-56 | 56 | 25 | 25 | 31 |
Polonium-212 | 212 | 84 | 84 | 128 |
Helium-4 | 4 | 2 | 2 | 2 |
Oxygen-16 | 16 | 8 | 8 | 8 |
( SORRY! I don't know how to connect both these tables XD *me no like computers*)
Mass Spectometers
- used to determine the abundance and mass of the isotopes of elements
.Sherilyn Tags.
Lesson 9 Quantum Mecahnics
· Bohr Theory
§ The electron is a particle that must be in orbital in the atom
· Quantum Theory
§ The electron is like a cloud of negative energy or a wave
§ Orbitals are areas in 3D space where the electrons most probably are
§ The energy of the electron is in its vibrational modes — like notes on a guitar string
§ Photons are produced when high energy modes change to lower energy modes
· S Orbitals (sphere)
§ There is 1 suborbitals
§ Each orbital holds 2 electrons
§ Total electrons = 2
· D Orbitals
§ There are 5 suborbitals
§ Each contains 2 electrons
§ Total electrons = 10
· F Orbitals
§ There are 7 suborbitals
§ Each contains 2 electrons
§ Total electrons = 14
1. The electron Configuration of Li
1s2, 2s1
Example #2
How many and what type of electrons are in Potassium
1s2, 2s2, 2p6, 3s2, 3p6, 4s1
Example #3
How many and what types of electrons are in Strontium ion
1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6
How many and what types of electrons are in Krypton
1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6
How many and what types of electrons are in Bromine ion
1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6
Example 3 are called isoelectronic
~ Kelly Bui~
LESSON 8 continued: Bohr's model
1. Draw the Bohr Diagram for the element: Aluminum Protons = 13
Atomic mass = 27
Neutrons = 27-13 = 14
3 Valence electrons (electrons in the outer shell)
2. Draw the Bohr Diagram for the element: Magnesium
Protons = 12
Atomic Mass = 24
Neutrons = 12
2 Valence electrons (outer shell)
· Bohr Model
Ø Atoms are electrically neutral
Ø Two different models can be used to describe electron configuration
§ Energy Level Model
o Electrons occupy shells which are divided into orbitals
¤ 2 e- in the first orbital
¤ 8 e- in the second orbital
¤ 8 e- in the second orbital
§ Bohr Model
· Energy Level Model
i.e. Phosphorus
· Bohr Diagram
i.e. Phosphorus
Protons = 15
Atomic Mass = 31
Neutron = 16
5 Valence electrons
~ Kelly Bui ~
LESSON 8 continued: Bohr's Model
BOHR (1920s)
> Rutherford's model was inherently unstable
- Protons and electrons should attract each other
> Matter emits light when it is heated (blackbody radiation)
> Light travels as photons
> The energy carried by photons depends on their wavelength
> Bohr based his model on the energy (light) emitted by different atoms
- Each atom has a specific spectra of light, and to explain this emission, Bohr suggested that electrons
occupy shells or orbitals
BOHR'S THEORY
> Electrons exist in orbitals
> When they absorb energy, they move to a higher orbital.
> As they fall from a higher orbital to a lower one, they release energy as a photon of light.
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| [ Photon of Light ] |
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»Loureal Agustin«
LESSON 8: Atomic Theory
Aristotle
[Four Element Theory]
> The four elements theory lasted for about 2000 years.
> It is not a scientific theory because it couldn't be tested against observation.
Democritus
> In 300 B.C., Democritus said atoms were indivisible particles
> First mention of atoms (atomos)
> Not a testable theory, only a conceptual model
> No mention of any atomic nucleus or its constituents
> Cannot be used to explain chemical reactions
Lavoisier (late 1700s)
> Law of conservation of mass
> Law of definite proportions
- water is always 11% H and 89% O
Proust (1799)
> If a compounds is broken down into its constituents, the products exist in the same ratio as in the compound.
> Experimentally proved Lavoisier Laws
Dalton (early 1800s)
> Atoms are solid, indestructible spheres (like Billiard balls)
> Provides for different elements (these would be different spheres)
> Based on the law of conservation of mass
> Having a molecule (atoms combine in simple whole # ratios) explains the law of constant composition
> If the atoms are not destroyed, mass does not change
←[TWINS]→
J.J. Thomson (1850s)
> Raisin Bun model
> Solid, positive spheres, with negative particles embedded in them
> First atomic theory to have + (protons) and - (electrons) charges
> Demonstrated the existence of electrons using a cathode ray tube
Rutherford...........'s assistant (1905)
> Showed that atoms have a positive, dense center with electrons outside it
> Resulted in a planetary model
> Explained why electrons spin around nucleus
> Suggests atoms are mostly empty space
~ Loureal & Kim
