question

[doxhund66]

i know this site is a lot more advanced than me (i'm only 8th grade Honors :oops: ) but it would be really helpful is someone could answer this question---
How do you find the # of protons and neutrons in an element :?: it would be great if someone could help me out. what i REALLY need 2 know is the # of protons/neutrons in Radium :? , that's the element i picked for my project. my science teacher explained all this, i just took really messy notes , and now i can't read them. ALL help is appreciated! thx. :lol:

[tamisa26]

what is the rare element in period 4, what is the lowest atomic mass lanthanide, what is the lowest atomic number actinide, lowest atomic number transuranium element,element with isotopic mass 209, element filling a 3d sublevel in Group 6/VIB, elements with five valence electrons in period 5,element with ten 4d electrons in period 5

[KathChem82]

what is the rare element in period 4, what is the lowest atomic mass lanthanide, what is the lowest atomic number actinide, lowest atomic number transuranium element,element with isotopic mass 209, element filling a 3d sublevel in Group 6/VIB, elements with five valence electrons in period 5,element with ten 4d electrons in period 5

1. Rare element in period 4
??

2. Lowest atomic mass lanthanide
Lanthanum, La = 138.91 amu

3. Lowest atomic number actinide
Actinium, Ac=89

4. Lowest atomic number transuranium element
Rutherfordium, Rf = 104

5. Element with isotopic mass 209
Polonium, Po

6. Element filling a 3d sublevel in group 6/VIB
Chromium, Cr

7. Element with 5 valence electrons in period 5
Antimony, Sb

8. Elements with 10 4d electrons in period 5
Pd, Ag, Cd, In, Sn, Sb, Te, I, Xe