עמוד:17 The atom’s charge is calculated as the difference between the number of positive charges ( the number of protons , which is also the atomic number ) and the number of negative charges ( the number of electrons ) . For example : The charge of an atom of gold than contains 79 protons and 79 electrons is : 79 – 79 = 0 The charge of the fluorine ion than contains 9 protons and 10 electrons is : 9 – 10 = -1 The charge of the magnesium ion than contains 12 protons and 10 electrons is : 12 – 10 = + 2 It is customary to write the ion charge in the upper right corner of the element symbol . If the charge is 1 , then besides the element symbol , only the + or – sign is written , representing the charge type ( positive or negative ) . If the charge is greater than 1 , then first the charge size is written , followed by its type . For example : The number of protons in the atom’s nucleus is what distinguishes one element from another , and this is known as the element’s atomic number . In a neutral atom , the number of protons equals the number of electrons . In an ion ( an electrically charged atom ) the number of electrons does not equal the number of protons . The ion’s charge is the difference between the number of protons and the number of electrons in the atom . Question In the following table write the atomic charge of each one of the elements , and determine whether it is a neutral atom or an ion .
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