1. How does the valence of an element relate to its chemical activity?
2. Identify the statements below as belonging to one of these laws: law of conservation of matter,
law of conversation of energy, or law of definite proportions.
a. Energy can be neither created nor destroyed by chemical means but can be changed from
one form to another.
b. The composition of a chemical compound never varies.
c. Matter can be neither created nor destroyed by chemical means but can be changed from
one form to another.
3. How was the Periodic Table of Elements developed and how are the elements arranged on it?

The number of valence electrons that an atom has dictates its ability to react chemically. The closer an atom is to achieving a full outermost shell, the more likely it will be to borrow electrons. Atoms are paired in a way that allows both to achieve a full stable outermost shell. For example, one atom of silicon has 14 electrons, four of which are valence electrons in the outermost shell. Silicon can lend, share, or gain four electrons to achieve a full outermost shell.

a. Law of conservation of energy

b. Law of definite proportions

c. Law of conservation of matter

Mendeleev first published a table of elements arranged according to increasing atomic masses. He noticed that some elements near each other had differing properties, but elements in vertical columns had similar properties. Moseley then rearranged the table according to atomic numbers and this eliminated the discrepancies found in Mendeleev’s attempt. Today’s version of the periodic table displays elements in order based on their atomic number; the atomic number indicates the number of protons within the atoms of a particular element. Rows are called periods and columns are called groups. Elements in the same group have similar properties. Elements are grouped into nine categories: noble gases, halogens, nonmetals, alkali metals, alkaline earth metals, transition metals, other metals, metalloids, and rare earth elements.

Explanation:

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