# Balancing Chemical Equations.

1. Li + H2O ->
2. K + H2O ->
3. Na + H2O ->
4. Ca + H2O ->
5. Mg + H2O ->
6. Cs + H2O ->
7. H + At ->
8. Na + At ->

## The Attempt at a Solution

1. 2Li + 2H2O -> H2 + 2LiOH
2 & 3: Same for 1.

Others I have no idea how to do. I was NOT taught these and she somehow thinks we were.

mgb_phys
Homework Helper
Do you have a periodic table?
Do you know about groups and valence?
So how many OH each of the metals needs to make a stabel compound.

ps. In your answer, how many H are on the right side of the equation?

Do you have a periodic table?
Do you know about groups and valence?
So how many OH each of the metals needs to make a stabel compound.

ps. In your answer, how many H are on the right side of the equation?

THe main problem is what the new product is. How would I know what Na + At, would create, etc,

mgb_phys
Homework Helper
Lithium is group 1 so it has one outer electron, and so it needs one OH group to plug into.
Sodium/Potassium are also group one, Magnesium and Calcium are group 2 so have 2 outer electrons and can plug into two OH groups

Lithium is group 1 so it has one outer electron, and so it needs one OH group to plug into.
Sodium/Potassium are also group one, Magnesium and Calcium are group 2 so have 2 outer electrons and can plug into two OH groups

I don't really understand. Can you show me examples?

Do you have a periodic table?

ps. In your answer, how many H are on the right side of the equation?

Four

mgb_phys
Homework Helper
Four

mgb_phys
Homework Helper
I don't really understand. Can you show me examples?
Do you know why it is 2Li + 2H2O -> H2 + 2LiOH ?

Lithium has 1 outer electron available for this sort of chemical reaction.
Oxygen is 2 electrons short.
Hydrogen is a little odd, it can be thought of as having one extra electron or one short - it has a single electron in an orbit that can hold 2.

The OH group has 2 spare slots on the oxygen and one of them filled by the hydrogen, so one free slot overall.
Lithium as we said has one extra electron which fits into this slot, making LiOH.
Magnesium has 2 outer electrons so needs to attach two OH groups = Mg(OH)2

Then it's just a matter of counting how many H2O you need to make everything balance.

Do you know why it is 2Li + 2H2O -> H2 + 2LiOH ?

Lithium has 1 outer electron available for this sort of chemical reaction.
Oxygen is 2 electrons short.
Hydrogen is a little odd, it can be thought of as having one extra electron or one short - it has a single electron in an orbit that can hold 2.

The OH group has 2 spare slots on the oxygen and one of them filled by the hydrogen, so one free slot overall.
Lithium as we said has one extra electron which fits into this slot, making LiOH.
Magnesium has 2 outer electrons so needs to attach two OH groups = Mg(OH)2

Then it's just a matter of counting how many H2O you need to make everything balance.

So then Mg + 2H2O -> H2 + Mg(OH)2

mgb_phys
Homework Helper
So then Mg + 2H2O -> H2 + Mg(OH)2

Correct.

Correct.

Good. What about Hydrogen and Astatine, and sodium and Astatine.

H + At = ... /kill myself

mgb_phys
Homework Helper
Bizarre example, Astatine (if you could get any) is chemically the same as Chlorine - what is the formula for Sodium and Chlorine

Bizarre example, Astatine (if you could get any) is chemically the same as Chlorine - what is the formula for Sodium and Chlorine

So Na + At -> NaAt

At + H - > AtH?

Yer, or HAt is normally the order.

mgb_phys
Homework Helper
And you have to balance it so that it's H2 or At2

And you have to balance it so that it's H2 or At2

Why?

mgb_phys