how many electrons are in the outer energy level of the atoms of alkaline-earth metals?
To determine the number of electrons in the outer energy level of alkaline-earth metals, you need to refer to the periodic table of elements. Here's how you can find the answer:
1. Locate the alkaline-earth metals: Alkaline-earth metals are found in Group 2 of the periodic table, which includes elements such as Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra).
2. Identify the atomic number: The atomic number of an element represents the number of protons in its nucleus. Locate the atomic number of the alkaline-earth metal you are interested in.
3. Determine the electron configuration: The electron configuration is a representation of how electrons are arranged in the energy levels (shells) around the nucleus. It is based on the Aufbau principle, which states that electrons fill lower energy levels before filling higher ones.
4. Count the electrons in the outermost energy level: Look at the electron configuration for the specific alkaline-earth metal. The outermost energy level is called the valence shell, and the electrons in this shell are called valence electrons. Count the number of valence electrons to determine how many electrons are in the outer energy level.
For example, let's take Calcium (Ca) as an alkaline-earth metal:
1. Locate Calcium on the periodic table.
2. The atomic number of Calcium is 20.
3. The electron configuration of Calcium is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s².
4. In the outermost energy level (4s), there are 2 electrons, so Calcium has 2 electrons in its outer energy level.
Therefore, alkaline-earth metals have 2 electrons in their outer energy level.