Atomic Mass Number



Has an atomic number double that of sodium’s. Has the lowest atomic number of any group 15 element. Is in group 1; has a higher atomic number than Cl but a lower atomic number than Br. Has between 35 and 55 protons and is in group 17. Has the lowest atomic mass on the periodic table. Each atom has a charged sub-structure consisting of a nucleus, which is made of protons and neutrons, surrounded by electrons. The number of protons and the mass number of an atom define the type of atom. Atoms of the same element with different mass numbers are called isotopes. The number of protons in an atom is known as the Atomic Number, which is how the periodic table is organized (they are listed in order of atomic number from left to right). The Mass Number describes the total number of protons and neutrons in the nucleus. An atom in its typical state will not have a charge, as the positive particles (protons) balanced out the negative ones (electrons).

If an atom has an atomic number of 9 and an atomic mass number of 19, how many protons, neutrons, and electrons does it have?

1 Answer

This isotope of fluorine has 9 protons, 9 electrons and 10 neutrons.

Explanation:

The atomic number is the number of protons #('p'^+')#. In a neutral atom, the number of electrons #('e'^(-)')# equals the number of protons. Mass number is the sum of the protons and neutrons #('n'^0')# of a particular isotope. If you have mass number and atomic number, subtract the atomic number from the mass number to get the number of neutrons. #('Mass number') - ('atomic number')='number of neutrons'#.

There are:
9 protons
9 electrons
10 neutrons

Fluorine is the element in question, as its atomic number is #9#. You would name this particular isotope using the mass number. It would be called fluorine-19.

The nuclear or isotopic notation would be #'_9^19'F'#.

Atomic Mass Number Definition

Atomic

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