you need
  • - periodic table of chemical elements DIMendeleev.
proton is a positively charged particle with a mass greater than 1836 times the mass of the electron.The electric charge of a proton is the same in absolute value with the charge of the electron, and hence the charge of the proton is equal to 1.6 * 10 ^ (-19) Pendant.The nuclei of different atoms contain different numbers of protons .For example, in the nucleus of the hydrogen atom only one proton, in its nucleus and gold - seventy nine.Number protons in the nucleus coincides with the serial number of the item in Table D.Mendeleev.Therefore, in order to determine the number protons in the nucleus of a chemical element, it is necessary to take the periodic table, to find in it the desired item.Said top integer is the atom
ic number - this is the number of protons in the nucleus.Example1.Suppose you need to determine the number of protons in its nucleus polonium.Search in the periodic table the chemical element polonium, it is located at No. 84, it means at its core is 84 protons.
Interestingly, the number of protons in the nucleus equals the number of electrons moving around the nucleus.That is the number of electrons in an atom of an element is determined as well as the number of protons - serial number of the item.Example 2: If the serial number of polonium - 84, in its 84 protons (in the core) and the same number - 84 electrons.
Neutron is an uncharged particle with a mass that is greater than the mass of the electron in 1839 again.In addition to the sequence number in the periodic table of chemical elements for each substance given another number, which, when rounded, shows the total number of particles ( protons and neutrons ) in the atomic nucleus.This number is called the mass number.To determine the number of neutrons in the nucleus must be subtracted from the number of the mass number protons .Example 3: The number of protons in an atom of polonium - 84. Its mass number is 210, then, to determine the number of neutrons find the difference between the mass number and serial number: 210 - 84 = 126.