The correct option is A. Rutherford model of the atom consider an atom to be made up of a central nucleus with electrons orbiting around it. The nucleus is considered to be tiny, heavy and its positively charged while the electrons are negatively charged. The shortcoming of this model is that it was not able to explain how the positive nucleus was not able to attract the negative electrons and pull them inside the nucleus.
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Answer:
A- beryllium
B- calcium
C- magnesium
Explanation
NOTE: all element in group 2 have 2 balance electrons
First let’s start with B- number of electrons= number of protons which is equal to the atomic number. therefore, the answer is calcium as it’s atomic number is 20
C- magnesium will have three energy levels considering it has 12 electrons (2,8,2).
A- beryllium is the lightest one in group 2 as it has the atomic mass of 9.0122.
Answer:
The ion is written in the attached file
Explanation: