It an element has 13 protons, 13 electrons and 15 neutrons what is its mass number?

28

Explanation:

The mass of an element, also called its atomic mass, can be calculated by adding the number of protons and neutrons.

P + N = mass

13 + 15 = 28

Therefore, the atomic mass is 28.

The number of electrons is generally not considered because they are so light, each of them weighs almost nothing.

each  column  of the  table  is called a group. elements in a group share similar properties. groups are  read  from  top  to  bottom. metal. metalloid. nonmetal. solid. liquid. gas. fe. hg. o.  2. 3. 4. 5. 6. 7. 8. 9.  2. beryllium. 9.012. 4.  sodium. 22.990.  11. 3.  magnesium. 24.305.  12.  potassium. 39.098.  19. 4.  calcium. 40.078.  20. i guess  i  

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