On the periodic table, lithium and beryllium are in different groups. Which statement describes why the two elements are in different groups? (1 point)
O They have a different number of electron shells.
O They have a different number of electrons in their outer shells.
They have different atomic numbers.
O They are different colors.
They have a different number of electrons in their outer shells.
The statement that describes why lithium and beryllium are in different groups on the periodic table is: They have a different number of electrons in their outer shells.
The correct statement that describes why lithium and beryllium are in different groups on the periodic table is: They have a different number of electrons in their outer shells.
To determine this, you can look at the electronic configuration of the elements. Lithium has an atomic number of 3, which means it has 3 electrons. The electronic configuration of lithium is 1s² 2s¹, where the superscript represents the number of electrons in each shell. The outermost shell of lithium, which is the 2s shell, contains 1 electron.
On the other hand, beryllium has an atomic number of 4, meaning it has 4 electrons. The electronic configuration of beryllium is 1s² 2s², indicating that its outermost shell, the 2s shell, contains 2 electrons.
Since lithium has 1 electron in its outer shell and beryllium has 2 electrons in its outer shell, they are placed in different groups on the periodic table. Elements within the same group generally have similar chemical properties due to their similar outer electron configurations.