help with krypton (Kr) and periodic table

Question

 

 

1.  the element kyrpton (kr) has an average atomic mass of 83.80.  this means that

 

a.  the average mass of  a mixture of krypton isotopes is 83.80

b.  all the atoms is a sample of krypton have an atomic mass of 83.80

c.  krpton has 83 protons

d.  kryton has 80 isotopes

 

I think the answer is a

 

2.  on the periodic table, elements are organized according to

 

a.  their properties

b.  increasing atomic number

c.  the number of electrons in their valance shelf

d.  all of these

 

I say answer is d

Answer 1

Good evening! Yes, the answer is "a". The mass shown on the periodic table is the average of all isotopes of an element (taking into account the relative abundances of each isotope.

 

Yes, the answer is "d". If you look at columns, those "families" all have the same number of valence electrons and therefore, the chemical behavior is the same for each member of a column. If you look at the rows, then as you move left to right, the atomic number (as indicated by the number of protons) increases.

 

Hope this helps

 

Mike

Answer 2

Hello, thank you for taking the time to post your question!

You got it for the first question! That one would be (a) because the atomic mass listed on the periodic table is a weighted average of the masses of all naturally occurring isotopes of that element.

Your response on the second question looks good as well … the primary organizing principle is the increasing atomic number, elements in the same group also have similar properties, and the elements in the same group have the same number of valence electrons, so it should be (d) all of these on that one.

I hope that helps get you moving in the right direction! Feel free to reach out if you have any additional questions beyond that :)