If an atom has 43 electrons, 56 neutrons, and 43 protons, what is its approximate atomic mass? What is the name of this element? periodic-table.png 

17 Divide:

Oxygen has an atomic number of 8. When it is uncharged, an oxygen atom will have __________ electrons in its outermost (valence) electron shell.

What is Gregor Mendel best known for?

Bacteria and viruses both belong to the domain bacteria. 

Bacteria and viruses both belong to the domain bacteria. 

Each chemical element has a unique atomic number, which indicates the number of ________ in its atoms.

Each chemical element has a unique atomic number, which indicates the number of ________ in its atoms.

Calculate the expression: x = 2+3. What is the value of x?

What can be concluded from this table?