3.Write the symbol of the element that has a charge of +1 when it has 71 electrons.

The symbol :

There are two components that accompany an element, the mass number and atomic number

Atoms are composed of 3 types of basic particles (subatomic particles): protons, electrons, and neutrons

The Atomic Number (Z) indicates the number of protons and electrons in an atom of an element.

Atomic number = number of protons = number of electrons ⇒ neutral number

Atomic mass is the sum of protons and neutrons

Atomic Number (Z) = Atomic mass (A) - Number of Neutrons

The element has 71 electrons and a charge of +1 , so

Number of protons = 71 + 1 = 72

Number of protons = the atomic number = 72

The element with atomic number 72 is Hafnium(Hf)

The atomic mass of Hf = 178 g/mol

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