Isotopes Lewis dot diagrams

and predicting reactions

Isotopes Lewis dot diagrams

and predicting reactions

But First, Let’s Review!!But First, Let’s Review!!

• Name the three subatomic particles that an atom is made of.

• Name the three subatomic particles that an atom is made of.

• Protons, neutrons, electrons

• Protons, neutrons, electrons

But First, Let’s Review!!But First, Let’s Review!!

• How do I calculate the number of protons?

• How do I calculate the number of protons?

• It’s the same as the atomic number!

• It’s the same as the atomic number!

But First, Let’s Review!!But First, Let’s Review!!

• How do I know how many neutrons there are?

• How do I know how many neutrons there are?

• Round the atomic mass and subtract the atomic number!

• Round the atomic mass and subtract the atomic number!

But First, Let’s Review!!But First, Let’s Review!!

• How do I know how many electrons there are?

• How do I know how many electrons there are?

• It’s the same as the number of protons! That’s how the charge of the atom stays neutral!

• It’s the same as the number of protons! That’s how the charge of the atom stays neutral!

But First, Let’s Review!!But First, Let’s Review!!

• Where does most of the atoms mass come from? AND what subatomic particles does it include?

• Where does most of the atoms mass come from? AND what subatomic particles does it include?

• The nucleus and it consists of protons and neutrons!

• The nucleus and it consists of protons and neutrons!

But First, Let’s Review!!But First, Let’s Review!!

• How many electrons are on the first, second an third shell?

• How many electrons are on the first, second an third shell?

• 2, 8, 8• 2, 8, 8

But First, Let’s Review!!But First, Let’s Review!!

• Who can draw a Bohr diagram for Sulfur?

• Who can draw a Bohr diagram for Sulfur?

Great Job! Great Job!

NOW we can learn more stuff! NOW we can learn more stuff!

IsotopesIsotopes

• Isotopes are another type of atom of the same chemical element with more neutrons.

• An isotope of Carbon, is still carbon it just has more neutrons in the nucleus.

• Having more neutrons does not affect the atomic number because the number of protons stays the same.

• Isotopes are another type of atom of the same chemical element with more neutrons.

• An isotope of Carbon, is still carbon it just has more neutrons in the nucleus.

• Having more neutrons does not affect the atomic number because the number of protons stays the same.

IsotopesIsotopes

• Some isotopes are radioactive while most are quite stable. • C14 is a radioactive form of Carbon,

where C12 and C13 are stable isotopes.

• C14 still has 6 protons (because the atomic number has not changed) but has 8 neutrons instead of 6.

• Some isotopes are radioactive while most are quite stable. • C14 is a radioactive form of Carbon,

where C12 and C13 are stable isotopes.

• C14 still has 6 protons (because the atomic number has not changed) but has 8 neutrons instead of 6.

Lewis dot DiagramsLewis dot Diagrams

• When predicting reactions, valence electrons are very important!!!

• Valence electrons- electrons that are on the outermost shell.

• Lewis dot diagrams are similar to Bohr Diagrams but they only show the outermost shell.

• When predicting reactions, valence electrons are very important!!!

• Valence electrons- electrons that are on the outermost shell.

• Lewis dot diagrams are similar to Bohr Diagrams but they only show the outermost shell.

Lewis dot DiagramsLewis dot Diagrams

• Bohr Diagram:

F

• Bohr Diagram:

F

• Lewis dot Diagram:

F

• Lewis dot Diagram:

F

Lewis dot DiagramsLewis dot Diagrams

• This diagram allows us to focus only on the valence electrons- which is all we really care about when predicting reactions.

• This diagram allows us to focus only on the valence electrons- which is all we really care about when predicting reactions.

Lewis dot DiagramsLewis dot Diagrams

• One more short-cut: Rather than have to draw a Bohr diagram first, or do the math to figure out the number of valence electrons- all you need to do is look at the number at the top of the column.

• EX: Phosphorus is in group 17, so it has 7 valence electrons.

• EX: Carbon is in group 14, it has 4 valence electrons

• EX: Hydrogen is in group 1, it has 1 valence electron

• One more short-cut: Rather than have to draw a Bohr diagram first, or do the math to figure out the number of valence electrons- all you need to do is look at the number at the top of the column.

• EX: Phosphorus is in group 17, so it has 7 valence electrons.

• EX: Carbon is in group 14, it has 4 valence electrons

• EX: Hydrogen is in group 1, it has 1 valence electron

Predicting ReactionsPredicting Reactions

• RULE 1: Everyone wants to be a noble gas!! The noble gasses are PERFECT. They have a full outer shell. All elements want to have a full outer shell.

• RULE 2: No one plays unless everyone is happy. All elements reacting must get what they want or no one reacts.

• RULE 1: Everyone wants to be a noble gas!! The noble gasses are PERFECT. They have a full outer shell. All elements want to have a full outer shell.

• RULE 2: No one plays unless everyone is happy. All elements reacting must get what they want or no one reacts.

Predicting ReactionsPredicting Reactions

• If I have Beryllium and Oxygen, how many atoms of each will I need to satisfy both rules? • Beryllium has 2 valence electrons

that it wants to get rid of. • Oxygen has 6 valence electrons and

needs to gain 2.

• If I have Beryllium and Oxygen, how many atoms of each will I need to satisfy both rules? • Beryllium has 2 valence electrons

that it wants to get rid of. • Oxygen has 6 valence electrons and

needs to gain 2.

Predicting ReactionsPredicting Reactions Be O Be O

We only need one of each! Beryllium is happy because it lost the two outer electrons, and went to its inner full shell. Oxygen is happy because with Berylliums two electrons it now has a full outer shell!

We only need one of each! Beryllium is happy because it lost the two outer electrons, and went to its inner full shell. Oxygen is happy because with Berylliums two electrons it now has a full outer shell!

Predicting ReactionsPredicting Reactions

• Atoms are lazy (like you!) and they don’t want to do too much work. If they only need to lose 1,2, or 3 electrons, they will do that rather than search for 5,6, or 7 to fill their shell.

• Atoms will do the least amount of work to gain or lose electrons in order to have a full outer shell.

• Remember 2 on the first shell is full! ! !

• Atoms are lazy (like you!) and they don’t want to do too much work. If they only need to lose 1,2, or 3 electrons, they will do that rather than search for 5,6, or 7 to fill their shell.

• Atoms will do the least amount of work to gain or lose electrons in order to have a full outer shell.

• Remember 2 on the first shell is full! ! !

Predicting Reactions: Lithium

Predicting Reactions: Lithium

• Lithium is atomic number 3 • How many protons does Lithium

have?• How many Neutrons does it have?• How many electrons does it have?• How many valence electrons does

it have? (What group is it in?)• What would a Bohr Diagram look

like for Lithium?

• Lithium is atomic number 3 • How many protons does Lithium

have?• How many Neutrons does it have?• How many electrons does it have?• How many valence electrons does

it have? (What group is it in?)• What would a Bohr Diagram look

like for Lithium?

Predicting Reactions: Lithium

Predicting Reactions: Lithium

• Will lithium try to lose it’s 1 electron? Or will it try to find 7? Which is easier?• Who is it lost likely to bond with?

Who needs to find an extra electron in order to be happy?• What will the charge of it be in the

end?

• Will lithium try to lose it’s 1 electron? Or will it try to find 7? Which is easier?• Who is it lost likely to bond with?

Who needs to find an extra electron in order to be happy?• What will the charge of it be in the

end?