Deduce the number of electrons in K + 19 40 .

For a neutral atom number of protons and number of electrons are equal. Number of protons in potassium is given as 19. So, number of electrons in the atom is 19. Potassium forms a positive ion which means that an electron is lost from the atom, therefore, number of electrons in K + , 19 - 1 = 18 .

Deduce the number of electrons in N 3 - 7 15 .

For a neutral atom number of protons and number of electrons are equal. Number of protons in nitrogen is given as 7. So, number of electrons in the atom is 7. Nitrogen forms negative ions which means that three electrons are gained by the atom, therefore, N 3 - , 7 + 3 = 10 electrons.

Deduce the number of electrons in O 2 - 8 18 .

For a neutral atom number of protons and number of electrons are equal. Number of protons in oxygen is given as 8. So, number of electrons in the atom is 8. Oxygen forms negative ions, which means that two electrons are gained by it to form a total of 10 electrons.

Deduce the number of electrons in Ga 3 + 31 71 .

Ions are charged particles formed by the loss or gain of electrons from an atom or group of covalently bonded atoms. For a neutral atom number of protons and number of electrons are equal. Number of protons in gallium is given as 31. So, number of electrons in the atom is 31. Gallium forms positive ions which means that three electrons are lost by the atom to form a total of 28 electrons.