15. what evidence convinced j. j. thomson that an atom consists of more than just electrons?\n16. a sample…

15.

Brief Explanations:

Atoms are neutral. Since electrons are negatively - charged, there must be a positive part to balance the charge. Thomson knew that atoms are neutral overall, so there had to be something positive in the atom to counterbalance the negative charge of electrons.

Answer:

The overall electrical neutrality of atoms. Atoms are neutral, but electrons are negatively charged, so there must be a positively - charged component in the atom.

16.

Explanation:

Step1: Identify the given values

The mass of the copper sample $m = 63.5$ g and the number of atoms $N=6.02\times 10^{23}$

Step2: Use the formula for mass of a single atom

The mass of a single atom $m_{single}=\frac{m}{N}$. Substitute $m = 63.5$ g and $N = 6.02\times 10^{23}$ into the formula. $m_{single}=\frac{63.5}{6.02\times 10^{23}}$ g $m_{single}=1.055\times 10^{-22}$ g

Answer:

$1.055\times 10^{-22}$ g

17.

Brief Explanations:

Dalton's atomic theory states that atoms of one element are different from atoms of other elements and that atoms are indivisible and indestructible in chemical reactions. So, atoms of one element cannot be converted into atoms of another in chemical reactions.

Answer:

No. According to Dalton's theory, atoms of one element are unique and cannot be changed into atoms of another element in chemical reactions as atoms are considered indivisible and indestructible in chemical processes.