1. Try This:
NH4C2H3O2
Type of atom
# of atoms N H C O
Kesteyscience

2. Bonding

3. Valence Electrons
Valence electrons are those electrons that are in the highest energy level (last energy shell)
The number of valence electrons in an atom of an element determines many properties of that element, including the ways in which the atom can bond with other atoms

4. Electron Dot Diagrams
An electron dot diagram includes the symbol for the element surrounded by dots. Each dot stands for one valence electron

5. Why do atoms bond together?
We are going to use the term “Happy Atoms”
Most atoms want to be happy! In order for atoms to be happy, their outer shells have to be full.
Some atoms have too many electrons so they like to get rid of their extra electrons. Some atoms have a shell that’s really close to being full. So these atoms look for other atoms that are giving their extra electrons away.
Look at the example on the screen. Sodium and Magnesium’s first two shells are completely filled. On their 3rd shells, there is a few extra electrons hanging out by themselves. What do we call these electrons? (VALENCE ELECTRONS). Sodium and Magnesium just want to be happy atoms! But right now, they aren’t happy.
So Sodium and Magnesium have two options: 1. They can either fill up their 3rd shell completely with 8 electrons or 2. They can give away their extra electrons. What do you think is the easier option? (GIVE AWAY).
Now they are on a hunt for an atom that has six or seven valence electrons to make them happy.

6. Oh Happy Day!
Would you look at that! Here are Oxygen and Flourine looking to gain some electrons. Because they want to be happy atoms too!
There are a few different ways that these atoms can get happy. They can share electrons, which makes a covalent bond. Or, they can just borrow the electrons, which makes an ionic bond.
Let’s see what happens when we get these shells full.

7. When Sodium (red) gets together with Fluorine (blue), they both end up as happy atoms! Now, Sodium has a full outer shell and so foes fluorine.
When an atom gives up an electron, it becomes positive. So which of the two elements will be positive? (Na+).
When an atom gains an electron, it becomes negatively charged. Fl-
The positive and negative charges attract to each other like magnets. The attraction of opposite charges is how atoms form and maintain (keep) the bond.

8. Why does bonding occur
Atoms want to become stable

9. Have 8 valence and are very unreactive
Stability
Most atoms are more stable --- less likely to react---- when they have eight valence electrons.
Have 8 valence and are very unreactive
Some small atoms are stable with two valence electrons in their first and only row

10. Reaching stability
In order for atoms to become stable they need to have a full outer energy level
Atoms want to become an octet
Octet-have 8 valence electrons
Exception hydrogen and helium because the outer energy level is stable with two electrons

11. How many more electrons are need to make the following elements stable?P Al Be Mg S Cl

12. Atoms usually react in a way that makes each atom more stable
One of two things can happen:
The number of valence electrons increase to 8
The atom gives up loosely held valence electrons or
Atoms that react this way become chemically combined- bonded to another atom

13. The Periodic Table
The periodic table is a system used worldwide for organizing elements into categories.
The way the elements are organized gives you important information about the arrangement of the electrons in their atoms

14. Periodic Table Gr
oups
As the number of protons (atomic number) increases, the number of electrons also increase
As a result, the properties of the elements change in a regular way across a period
A row of elements across the periodic table is called a period

15. How the Periodic Table Works
As the number of protons (atomic number) increase, the number of electrons also increases
The elements within a group have similar properties because they all have the same number of valence electrons in their atoms

16. Noble Gases
Group 18 elements are known as the noble gases
Atoms of these elements have 8 valence electrons- except for helium which has _______

17. As a result, noble gases do not react easily with other elements
Remember when atoms get the maximum number of valence electrons they become stable
The variety of colors in a “neon” sign results from passing an electric current through sealed glass tubes containing different noble gases
As a result, noble gases do not react easily with other elements

19. Now look at the elements in the column just to the left of the noble gases Group 17 are called the
Halogens

20. Halogens Atoms in the halogen family have ____ valence electrons
A gain of just one more electron gives these atoms the stable number of 8 electrons
As a result, elements in the halogen family react easily with other elements whose atoms can give up or share electrons

21. Atoms of alkali metals have only _____valence electron
Group 1 is called the
Alkali Metal
Family
Atoms of alkali metals have only _____valence electron
except for lithium
The energy level below this single electron contains a stable set of 8 electrons
Has a stable set of two electrons in the energy level below the valence electron

23. Alkali metal
can become chemically more stable by losing their 1 valence electron
This property makes the alkali metals very reactive

24. (a halogen) reacts with aluminum, a purple gas is produced
Elements in Group 17(the Halogens) and Group 1(the alkali metals) are highly reactive
When iodine
(a halogen) reacts with aluminum, a purple gas is produced
Sodium (an alkali metal) reacts vigorously with bromine (a halogen)

25. Other Metals… Most have 1, 2, or 3 valence electrons
Look at the elements in Group 2 through 12
Most have 1, 2, or 3 valence electrons
They react by losing these electrons, especially when they combine with oxygen or one of the halogens

26. Other Metals
How reactive a metal is depends on how easily its atoms lose valence electrons
They react by losing these electrons, especially when they combine with oxygen or one of the halogens

27. Nonmetals combine with metals usually by gaining electrons
But nonmetals can also combine with other nonmetals by SHARING electrons
Of the nonmetals oxygen and the halogens are highly reactive
In fact, FLOURINE is the most REACTIVE element known
It even forms compounds with some of the noble gases

28. Metalloids
Several elements known as metalloids lie along a zigzag line between the metals
and
nonmetals
Quartz- movement watch keeps time with a small quartz crystal, a compound made of the metalloid silicon and the nonmetal oxygen
The metalloids have from 3 to 6 valence electrons and can either lose or share electrons when they combine with other elements

29. Hydrogen Hydrogen is considered to be a nonmetal
It is located above Group 1 in the periodic table because it has only one valence electron
However, even though hydrogen is a reactive element, its properties differ greatly from those of the alkali metals