14 A teacher gives her students a paper plate, glue, 10 black beads (electrons), 10 blue beads (neutrons) and 10 red beads (protons). The students are to glue the beads onto the
paper plate to construct an atom. One student chooses to construct Magnesium and finds
out that he doesn't have enough beads. How many more beads of each color does he need
to correctly construct the atom?
A.2 black, 2 blue, 2 red
B.1 black, 1 blue, 1 red
C.3 black, 2 blue, 1 red
D.3 black, 3 blue, 3 red

it's c. elements are placed in rows based on how may valencies electrons have.

im pretty sure its b

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.