# Hydrogen 4+

1. Apr 24, 2012

### jessiewills

What is the energy of the n = 1 energy level in the
B4+ hydrogen-like ion?
I need it to 4 significant figures...
I know the equation is

En=Z squared X -13.60 /n squared..... however I cant work out the answer to four significant figs

2. Apr 24, 2012

### phyzguy

Why not? You have 13.60 to 4 significant figures. What is Z? What is n?

3. Apr 24, 2012

### jessiewills

Z= 5 for the B and the n= 1 for the energy?

4. Apr 24, 2012

### phyzguy

Sounds good. So what's the answer?

5. Apr 24, 2012

### jessiewills

-340...but its needed in 4 significant figures? and i really dont understand how i can get that too it...im dumb :/

6. Apr 24, 2012

### phyzguy

You started with 13.6, but it was 13.60 to 4 significant figures, so what is 340 to 4 significant figures?

7. Apr 24, 2012

### jessiewills

340.0.....really? that simple also do i need to keep it to minus or does it change?

8. Apr 24, 2012

### phyzguy

It's that simple. Yes, it is negative as you originally had it.