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E N E R G Y A N D C O N F I G U R A T I O N

The Atom

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Radioactivity

Series of DiscoveriesWilhelm Roentgen: Discovered a ray that could travel

through walls. These rays were emitted from a dischargetube enclosed in black cardboard box made a piece of

paper, coated with Barium platinocyanide glow. Hecalled them X-rays.

Henri Becquerel experimented a sample of uraniumcompound. He noticed that the uranium compound was

able to expose films that are sealed inside a box. This iscaused by the penetrating rays of the uraniumcompound.

Marie Curie named this radioactivity.

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Radioactivity

Earnest Rutherford did the same experiment withUranium and was able to determine the differentrays with another experiment by observing the raysas the pass through a magnetic field.

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Radioactivity

Radioactive Decay- is the process in which anunstable atomic nucleus spontaneously loses energy

by emitting ionizing particles and radiation.

Radiation - any process in which energy emitted byone body travels through a medium or throughspace, ultimately to be absorbed by another body.

Ionizing Radiation Knocks off an electron

ionizing an atom, thus giving the atom a positivecharge.

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Radioactivity

Alpha Radiation The release of 2 protons and 2neutrons.

Beta Radiation The release of an electron or

positron and proton due to the decomposition ofneutron.

Gamma Radiation Emitted by the atoms due tosub-particle interactions. It has no charge. The

reason why it is not affected by a magnetic energyfield. The most penetrating radiation among the 3rays.

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Ions and Isotopes

*Due to the behavior of atoms, they have the tendency tolose or gain electrons. The protons usually stays in thenucleus.

Ions exists due to the increase and decrease of thenumber of the electron. Came from a Greek wordmeaning Wanderer. Discovered by Michael Faraday.

AnionGreek word Ana meaning Up, the moleculegains more electron hence making it negatively charged.

CationKata meaning down, atom loses electronsthus giving them a positive charge.

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Ions and Isotopes

Isotopes - are similar elements with different masses.They have the same number of protons and electrons

but have different number of neutrons.

Ex: Z A e p n %Lithium 6 3 6 3 3 3 7.5

Lithium 7 3 7 3 3 3 92.5

Carbon 12 6 12 6 6 6 98.90

Carbon 13 6 13 6 6 7 1.10

Carbon 14 6 14 6 6 8 n/a

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Electron Configuration

Principal Energy Level These are theenergy levels designated by the letter nwhich is a positive integer.

The ground state the lowest energy levelcorresponds to n=1, then the succeeding

would be n=2, n=3, n=4, n=5, n=6, n=7

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Electron Configuration

Sub-energy levels (Subshells) contained by eachprinciple energy level with letter designations.

s = sharp 2 electrons in subshell (1 subshell)p = principle 6 electrons in subshell (3 subshell)

d = diffuse 10 electrons in subshell (5 subshell)

f = fundamental

14 electrons in subshell (7subshell)

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Electron Configuration

Types of Orbitals

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Electron Configuration

The following rules determine what types of energysublevels occur in a given energy level and the maximumnumber of electrons in the energy level.

The Aufbau Principle

According to the principle, electrons fill orbitals startingat the lowest available energy states before filling higherstates (e.g. 1s before 2s).

from the German Aufbau meaning "building up,construction": alsoAufbau rule orbuilding-upprinciple.

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Electron Configuration

Hunds Rule

1. No more than 2 electrons can occupy 1 orbital

2. Electrons occupy the lowest possible energy levels;they enter a higher energy level only when thelower sublevels are filled

3. Orbitals in a given sublevel of equal energy are eachoccupied by a single electron before a secondelectron enters them.

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Electron Configuration