The Law of Conservation of requires that chemical equations are balance with the
reactant atoms being equal to the product atoms.

True.

Explanation:

Hello!

In this case, since the law of conservation of mass and energy states that both mass and energy cannot be neither created nor destroyed, if we want to analyze it in a chemical reaction, it is necessary to realize that the initial reactants are composed by a specific amount of atoms of each element and therefore the products must have that equal amount. For instance, going over the formation of water from hydrogen and oxygen:

We can see hydrogen are equal at both sides whereas oxygen do not; that is why we balance it by putting a coefficient of 2 just before hydrogen and water in order to equal the new 4 atoms of H and 2 atoms of O at each side.

That is why this statement is true.

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

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since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.