Answer:
Explanation:
Dmitri Mendeleev developed a chart-like arrangement of the elements called the Periodic Table ______ . He stated that if the elements were listed in order of increasing atomic mass______, their properties repeated in a regular manner. He called this the periodicity of properties ______ of the elements. The arrangement used today differs from that of Mendeleev in that the elements are arranged in order of increasing atomic number______. Each horizontal row of elements is called a(n)period ______. Each vertical column is called a(n) column_____, or , because of the resemblance between elements in the same column, a(n) __group____.
Answer:
Sr, Mg, P, F
Explanation:
The trend for decreasing radii size is up and to the right of the Periodic Table.
Boron (B) has 3 electrons in the outer shell.
Barium (Ba) has 2 electrons.
Phosphorus (P) has 5 electrons.
Manganese (Mn) has 2 electrons.
The answer is C) P (phosphorus).
