1. 4.1 Atomic Theory & Bonding
ATOM: smallest particle of an element that still retains the properties of that element. All atoms are made of the following parts: PEN = proton(s) + electron(s) + neutron(s) These ‘parts’ that make up the atom are known as: _______ ___________ ___________

2. Structure of an Atom:

4. All atoms have a ________ charge because they have the same number of
___________ & ___________. Therefore, they charges cancel each other out!

5. Atomic structures of other elements

6. Here is Carbon again, just drawn another way!
The actual size of this atom of Carbon is not accurate! Why?

8. For our sake, we will draw atoms with a
visible nucleus!

9. ELEMENT: made up of 1 type of atom Examples in Biology: Examples in Mining: Other Examples:

10. Other examples of compounds?
COMPOUNDS: are made up of at least 2 atoms bonded together.
Hydrogen and oxygen are atoms/elements
H2O is a compound
Other examples of compounds?

11. Where are the following?
INCREASING REACTIVITY
Where are the following?
Atomic Number
Period
Group/Family
Metals
Non-metals
Transition metals
Metalloids
Alkali metals
Alkaline earth metals
Halogens
Noble gases

12. Families of the Periodic Table:
Columns of elements are called groups, or families
All elements in a family have…
similar properties
bond with other elements in similar ways
have the same number of valence electrons
Family names (on the periodic table!):
Group 1 = alkali metals (1+, highly reactive)
Group 2 = alkaline earth metals (2+, reactive)
Group 17 = the halogens (1-, very reactive)
Group 18 = noble gases (0, unreactive)
Periods are horizontal rows on the periodic table.

13. Periodic Table & Ion Formation:
Ions: Atoms will gain and lose electrons to become ____.
It is very rare to find atoms of any element in nature. It is more likely to find them in a compound.
Atoms, like humans, just want to be stable.
Stability is reached for an atom when they have a full outer shell of electrons.
This outer shell of electrons is called the ________ shell.

14. Niels Bohr ( )
Niels discovered something special about an atom’s electrons….What was it?? See Fig 4.5

16. Bohr Diagrams:
Bohr diagrams show how many electrons appear in each electron shell around an atom. (2, 8, 8, 18, 18)
Valence electrons: electrons in the outermost shell ONLY.
If the valence shell is full = stable
If the valence shell is not full = reactive

20. Bohr Diagrams What element is this?
It has = 18 electrons, and therefore 18 protons
It has 8 electrons in the outer (valence) shell
18 p
22 n
Argon!

21. Electrons are transferred from the cations to the anion
Ionic Bonds:
Formed between Metals (cations) & non-metals (anions).
Valence electrons are transferred from metal to nonmetal.
Eg. Li2O
Lithium
Oxygen +
Electrons are transferred from the cations to the anion
Li+ O2- Li+
Lithium oxide,
Li2O
Covalent Bonds:
Formed between two or more non-metals
Valence electrons are shared between atoms
Eg. HF
Hydrogen
Fluorine +
Electrons are shared
Hydrogen fluoride

22. Lewis Diagrams: Ex: Nitrogen atom Only valence electrons are shown
Dots representing valence electrons are placed around the element symbols (on 4 sides, imagine a box around the symbol)
Electron dots are placed singularly,
then they are paired.
Ex: Nitrogen atom

25. Lewis Diagrams for Ions:
Ex. Nitrogen ion
Remove or add electron dots to
make full valence shells.
Square brackets and the charge
are placed around each ion 2+ – –
• •
• •
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• •
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• •
• •
• •
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• •
• •
• •
• •
• •
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• • Be Cl Cl Be Cl Cl Be Cl
Since Be2+ wants to donate 2 electrons and each Cl– wants to accept only one, two Cl– ions are necessary
Each beryllium has two electrons to transfer away, and each chlorine wants one more electron
The ionic compound Beryllium chloride is formed

26. Lewis Diagrams For Covalent Bonds:
valence electrons are drawn to show sharing of electrons.
Remember: All atoms “like” to have a full valence shell
The shared pairs (“bonding pairs”) of electrons are usually drawn as a straight line
“lone pairs” are the electrons not shared