Predict how many electrons will most likely be gained or lost by each of the following elements.
(a) Se
Will it gain or lose electrons?
gain
lose
number of electrons
(b) Cl
Will it gain or lose electrons?
gain
lose
number of electrons
(c) Al
Will it gain or lose electrons?
gain
lose
number of electrons
(d) Ba
Will it gain or lose electrons?
gain
lose
number of electrons
How do you know if it will lose or gain electrons.
Look at the periodic table.
If the element is in groups I, II, or III (or groups 1, 2, and 13 depending upon the system your prof is using), the element has an extra 1, 2, or 3 electrons in the outer shell and will lose 1, 2, or 3 electrons. If the element is in group V, VI, or VIII (or groups 15, 16, 17), it has 5, 6, or 7 electrons in the outer shell and will GAIN 3 electrons (to make 8 from 5), gain 2 electrons (to make 8 from 6) or gain 1 electron (to make 8 from 7).
Elements in group 0 (or 18) already have 8 electrons in their outer shell and they neither gain nor lose electrons. Group IV (group 14) elements have 4 electrons in their outer shell and usually neither gain nor lose; rather they almost always SHARE electrons to complete their outer shells.
You know the tendency from its position on the periodic table. Metals lose electrons.
(a) Se will most likely gain electrons.
(b) Cl will most likely gain electrons.
(c) Al will most likely lose electrons.
(d) Ba will most likely lose electrons.
You can determine whether an element will gain or lose electrons based on its position in the periodic table and its valence electrons.
Elements on the left side of the periodic table (Group 1 and 2) tend to lose electrons to achieve a stable noble gas electron configuration.
Elements on the right side of the periodic table (Group 16 and 17) tend to gain electrons to achieve a stable noble gas electron configuration.
For example, Se is in Group 16, so it will likely gain electrons to achieve a stable electron configuration similar to that of a noble gas. Meanwhile, Cl is also in Group 16 and will also gain electrons. On the other hand, Al is in Group 13 and Ba is in Group 2. Both Al and Ba will tend to lose electrons to achieve a stable noble gas electron configuration.
To determine whether an element will gain or lose electrons, you can refer to its position in the periodic table.
(a) Se (selenium) is found in group 16, also known as the oxygen group. Elements in this group tend to gain 2 electrons to achieve a stable electron configuration, so Se is likely to gain 2 electrons.
(b) Cl (chlorine) is found in group 17, known as the halogens. Halogens have 7 valence electrons and they tend to gain one more electron to achieve a stable electron configuration. Therefore, Cl is likely to gain 1 electron.
(c) Al (aluminum) is found in group 13, also known as the boron group. Elements in this group tend to lose 3 electrons to achieve a stable electron configuration. Therefore, Al is likely to lose 3 electrons.
(d) Ba (barium) is found in group 2, known as the alkaline earth metals. Alkaline earth metals have 2 valence electrons and they tend to lose these 2 electrons to achieve a stable electron configuration. Therefore, Ba is likely to lose 2 electrons.
Remember, these predictions are based on general trends in the periodic table, and actual electron changes can also depend on other factors such as the presence of other elements or specific chemical reactions.