A student created a model to explain half-life during alpha decay using 50 pennies and a plastic container with a lid. He began by placing all the pennies in the container with the heads side facing up. He closed the container and shook it five times. He opened the container and removed any pennies with the tails side facing up. He alternated shaking the container with removing the "tails" pennies until the container was empty. In this model, what do the pennies showing tails represent?

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

that's it!

if you need further assistance, let me know: )

~ trueboss72

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.