Using the Bohr model, determine the number of valence electrons in an aluminum atom.
Answer (2)
Aluminum has 13 electrons.
The electron configuration is determined by filling the shells: 2 electrons in the first shell, 8 in the second, and 3 in the third.
Valence electrons are those in the outermost shell.
Aluminum has 3 valence electrons.
Explanation
Understanding Aluminum and the Bohr Model Aluminum (Al) has an atomic number of 13, meaning it has 13 electrons. According to the Bohr model, electrons occupy specific energy levels or shells around the nucleus. The first shell can hold up to 2 electrons, the second shell can hold up to 8 electrons, and the third shell can hold up to 18 electrons. Valence electrons are those in the outermost shell of an atom; these are the electrons involved in chemical bonding.
Filling the Electron Shells We need to determine how the 13 electrons of aluminum are arranged in the shells. The first shell is filled first, then the second, and so on.
Distributing the Electrons
First Shell: The first shell can hold a maximum of 2 electrons. So, we place 2 electrons in the first shell. This leaves us with 13 − 2 = 11 electrons.
Second Shell: The second shell can hold a maximum of 8 electrons. We place 8 electrons in the second shell. This leaves us with 11 − 8 = 3 electrons.
Third Shell: The remaining 3 electrons are placed in the third shell.
Identifying Valence Electrons The electron configuration of aluminum is 2 electrons in the first shell, 8 electrons in the second shell, and 3 electrons in the third shell. The valence electrons are the electrons in the outermost shell, which in this case is the third shell. Therefore, aluminum has 3 valence electrons.
Final Answer The number of valence electrons in an aluminum atom, according to the Bohr model, is 3.
Examples
Understanding valence electrons is crucial in chemistry. For example, aluminum oxide ( A l 2 O 3 ) is a common compound. The fact that aluminum has 3 valence electrons and oxygen has 6 (or needs 2 more to complete its octet) explains why two aluminum atoms combine with three oxygen atoms. This knowledge helps predict how elements will interact and form compounds, which is fundamental in material science and chemical engineering.
An aluminum atom has 13 electrons with an electron configuration of 2 in the first shell, 8 in the second, and 3 in the third shell. Therefore, aluminum has 3 valence electrons. These are the electrons that are involved in chemical bonding.
;
