what do the elements in these groups have in common
a) alkali metals
b) halogens
c) noble gases
The correct answer and explanation is:
Correct Answer:
a) Alkali metals: All elements have one valence electron.
b) Halogens: All elements have seven valence electrons.
c) Noble gases: All elements have full outer electron shells.
Explanation:
Elements are grouped in the periodic table based on similar chemical and physical properties. Each vertical column is called a group or family, and elements in the same group share key characteristics because they have the same number of electrons in their outermost shell, known as valence electrons. This determines how they react chemically.
a) Alkali metals belong to Group 1 of the periodic table and include elements like lithium, sodium, and potassium. These metals all have one electron in their outer shell. Because of this, they are highly reactive, especially with water, and are rarely found in pure form in nature. The single valence electron is easily lost during chemical reactions, which makes these elements form +1 ions readily. They are soft, shiny metals with low melting points compared to other metals.
b) Halogens are found in Group 17 and include fluorine, chlorine, bromine, and iodine. Each halogen has seven valence electrons, making them one electron short of a full shell. This causes them to be very reactive, especially with alkali metals and alkaline earth metals, as they tend to gain one electron to achieve a stable configuration. They often form -1 ions and are found in various physical states: gases, liquids, and solids at room temperature.
c) Noble gases are in Group 18 and include helium, neon, argon, and others. All noble gases have full outer electron shells, which makes them extremely stable and unreactive. Because their shells are complete, they do not tend to gain or lose electrons, and they rarely form compounds. They are all gases at room temperature and are used in lighting, balloons, and inert environments for chemical reactions.