The mass of one atom is almost all as result of the protons and also neutrons in the nucleus. The atom mass number is the variety of protons included to the number of neutrons and also is provided the price A. Because that this atom the lithium, A equates to 6.

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The variety of protons in the cell nucleus of an atom is referred to as the atomic number. It has the price Z. The atomic variety of lithium is 3.

We can present the atomic mass number and the atom number with the symbol because that the element.

Structure of cell nucleus graphicPicture 2.4 mirroring the atom number and mass number of an atom. Notification that castle come before the symbol. A is at the top and Z is in ~ the bottom.Symbols because that atomsNitrogen has an atomic variety of 7 (Z=7) because it has actually 7 proton in that nucleus. Some nitrogen atoms have actually an atomic mass variety of 15 (A=15).

A is the number of neutrons plus protons in the nucleus.However, we already know that there are 7 protons. Therefore, there need to be 8 neutron in the cell nucleus to add up to 15.

Neutrons and also isotopesThe nucleus of every nitrogen atom has actually 7 ptotons. However, the variety of neutrons can vary. This provides rise to different isotopes (see web page 9). Few of these isotopes will be radioactive.

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navigation barQuestion 7Look at the symbols below. In every case, decision on the absent information and form it into the space.
a) carbon 14i. atomic numberii. number of protonsiii. number the neutronsb) oxygen 17i. atomic fixed numberiii. number of neutronsc) helium 4i. Aii. Ziii. number the neutrons