The fixed of an atom is nearly all because of the protons and neutrons in the nucleus. The atom mass number is the variety of protons added to the number of neutrons and is given the price A. Because that this atom of lithium, A equals 6.

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The variety of protons in the cell nucleus of one atom is dubbed the atomic number. It has the prize Z. The atomic number of lithium is 3.

We can show the atomic mass number and the atomic number through the symbol for the element.

Structure of cell core graphicPicture 2.4 reflecting the atom number and also mass variety of an atom. An alert that castle come prior to the symbol. A is in ~ the top and also 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. Part nitrogen atoms have an atomic mass number of 15 (A=15).

A is the number of neutrons plus proton in the nucleus.However, we already know the there are 7 protons. Therefore, there should be 8 neutrons in the nucleus to add up come 15.

Neutrons and isotopesThe cell core of every nitrogen atom has actually 7 ptotons. However, the variety of neutrons have the right to vary. This offers rise to various isotopes (see web page 9). Some of these isotopes will be radioactive.

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