IB Chemistry midterm

Empirical Formula
The ratios of atoms in a molecule. It looks like a molecular formula, but may be different. A compound X2Y4 would have an empirial formula of XY2.
Relative Atomic Mass

The average atomic mass of all of an atom’s isotopes, taking into account how common they are.


You will be given information about the masses of each isotope and how common it is. Make the percentages into decimals, multiply each by the mass they’re talking about, and then add together to get the average.

Avogadro’s Number
6.02 x 10 ^23
Avogadro’s Law
Equal volumes of ideal gases at STP contain equal number of molecules.
Ideal Gas Law
What is the difference between a line spectrum and a continuous spectrum?

Continuous spectra contain all colors (frequencies). Line spectra only contain a few.


Continuous spectra are produced by liquids and gases under high pressure. Line spectra are produced under low pressure.

When an energy level drops to n=3, it emits this type of wavelength.
Infrared (shortest.)

When an energy level drops to n=2, it produces this type of wavelength.



Visible light (middle)
Any energy level drop to n=1 emits this type of wavelength.
Ultraviolet (longest)

How are the lines in the emission spectrum of hydrogen related to the energy levels of electrons? 

I don’t really understand this question. Someone please enlighten me?
Where are protons located in the atom?
Where are neutrons located in the atom?
Nucleus. You really should know this stuff.

Where are electrons located in the atom?


The electron cloud.
Compared to neutrons and protons, the size of an electron is…
very very tiny!
An atom with a different number of protons. (Carbon-13, etc.)