1. Atomic Structure and The Periodic Table

2. A Brief History

3. John Dalton Father of Atomic Theory
Proposed that all matter was made up of atoms
Dalton's Atomic Theory
1) All matter is made of atoms. Atoms are indivisible and indestructible.
2) All atoms of a given element are identical in mass and properties
3) Compounds are formed by a combination of two or more different kinds of atoms.
4) A chemical reaction is a rearrangement of atoms.

4. John Dalton
Modern atomic theory is, of course, a little more involved than Dalton's theory but the essence of Dalton's theory remains valid.
Today we know that atoms can be destroyed via nuclear reactions but not by chemical reactions. Also, there are different kinds of atoms (differing by their masses) within an element that are known as "isotopes", but isotopes of an element have the same chemical properties.

5. Rutherford Gold Foil Experiment

6. Rutherford Gold Foil Experiment
The results of this experiment gave Rutherford the means to arrive at two conclusions: 
an atom was much more than just empty space and scattered electrons
an atom must have a positively charged center that contains most of its mass (which Rutherford termed as the nucleus).

7. Atomic Structure Atoms are made out of :
Protons = Positively Charged particles that are found in the nucleus. They have the same charge as an electron but their charge is positive.
Neutrons = Neutral charge, also found in the nucleus.
Electrons = Much smaller than protons and neutrons, but have an equal negative charge to that of the protons. They are found orbiting the nucleus of the atom. (Actually found in dense clouds)
Atoms are made out of :

8. The Periodic Table

9. Atomic Number and Mass The Atomic Number = Number of Protons (P+)
The Atomic Mass = Number of Protons and Neutrons (P++N)
Every element on the periodic table is neutrally charged, therefore it has an equal number of protons and electrons.
Therefore the atomic number can also tell you the number of electrons(e-) IF it is NOT an ION.
An Ion is a charged Atom, meaning it has more or less electrons than protons making it positively or negatively charged. (MORE ON THIS LATER)

10. Periods vs Groups
Periods are rows in the periodic table. No similarity in chemical properties.
Groups or families are columns in the periodic table. Similar Chemical and Physical properties throughout.

11. Periodic Law
Periodic Law is that the Periodic Table is arranged in increasing atomic number. (Going across in a period)
NOT MASS!
This specific arrangement of atoms causes specific trends to form in the periodic table.

12. Metal vs Non-Metals
All the metals are found on the left hand side of the step in the period table.
All the non-metals are found on the right hand side of the periodic table.
Metalloids have some characteristics of metals and some of non metals

13. Electron Arrangement
Electrons are arranged in orbits(clouds) around the nucleus of an atoms.
Each orbit can only fit a certain number of electrons in it.

14. Valence Electrons
Valence Electrons are the numbers of electrons in the outer shell.

15. Families/groups in the Periodic Table and their trends
Because all elements in a group/family have the same number of valence electrons, they have similar chemical and physical properties.

16. Group 1 – Alkali Metals All shiny, soft metals.
Chemical reactivity increases as you go down the period because it is easier for the atom to lose its valence electron. (Less attraction between positive nucleus and valence electron)
React violently with water

17. Group 2 – Alkali Earth Metals
Also Shiny relatively soft metals
Not as reactive as Alkali metals
Reactivity also increases as you go down the group
Also reacts with water

18. Groups 3-12 – Transition metals
These are all important metals used in industry
Ductile (Used to make wires), Malleable ( Can be worked), and can conduct heat and electricity well.

19. Group 17 – Halogens
Toxic non-metals, mostly gases at room temperature.
Chemical reactivity decreases as you go down the group
Fluorine is the most reactive of the group.
The reason why reactivity decreases is because it is easier for Fluorine to attract an electron than any other elements in the group.

20. Group 18 – Noble Gases All inert gases at room temperature
All these elements are totally unreactive because they all have a full outer shell, which means they have 8 valence electrons.

21. Octet Rule
Octet Rule All atoms want to be like the nearest noble gas, therefore they want to either gain or lose electrons so they will have 8 ELECTRONS in their outer shell.
This is the basis for all chemistry. The reason why chemicals react is because the reactants are trying to fill up their outer shell.
Ion – When an atom either gains or loses an electron it becomes an ion because it has more or less electrons than protons.
An Ion is a charged atom.

22. Determining the Charge of An Atom
The charge of an atom can be determined by determining how many electrons are needed to fill the outer shell of an electron.
The octet rule states that every atom wants to have 8 electrons in its outer shell (besides hydrogen and helium which want 2)
Therefore, if for instance we have an atom of Aluminum that has 3 valance electrons. You have to ask yourself, is it easier for it to gain 5 electrons of lose 3 electrons to get a full outer shell???
What do you think??
Lose 3 e-

23. Determining the Charge of an Atom
Aluminum = 13 P+ 13 e- in ground state
Al is a group 3/13 element therefore it has 3 valence electrons. (3 outer shell electrons)
To become an Ion it must lose 3 e- , therefore its charge will be +3.
Why? Well the number of protons cannot change, and now Aluminum has 10 e-
13 P+ = (13 x +1) = +13
10 e- = (13 x -1) = -10 +3

24. Types of Ions Anions – Usually non-metals and are NEGATIVELY CHARGED
Cations - Usually metals and are POSITIVELY CHARGED

25. Practice
What is the charge of the following elements? Na F O P Mg

26. Answers
Na = +1
F = -1
O = -2
P = -3
Mg = +2

27. Isotopes
Isotopes are atoms of the same elements that have the same number of protons but different numbers of neutrons.
Isotopes have many uses like…..
Radiometric dating, nuclear power etc..
Isotope Notation
Isotope Name - Atomic Number Element - Atomic Mass
Uranium - 235

28. Atomic Spectrum
When electromagnetic radiation of a specific wavelength is supplied to an atom it will cause the electrons to jump their energy levels and emit and absorb energy themselves. Every element on the periodic table has a unique atomic spectrum.

30. Atomic Spectra
If a known atomic spectra and an unknown atomic spectra match up, then the two materials are the exact same.
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