Question

5 multiple answer 1 point
$^{35}$cl- and $^{37}$cl- have the same number of... (check all that apply.)
neutrons
atomic mass units
protons
electrons
6 multiple choice 1 point
mendeleevs periodic table had one unique characteristic that is often called genius. what is that characteristic?
arrangement by atomic mass
arrangement by properties
gaps left where elements were not yet discovered
arrangement by atomic number

Explanation:

Question 5 (Multiple Answer)

Step1: Analyze \(^{35}\text{Cl}^-\) and \(^{37}\text{Cl}^-\)

For chlorine, atomic number \(Z = 17\), so number of protons \(= 17\) for both.
For \(^{35}\text{Cl}^-\): mass number \(A = 35\), neutrons \(= A - Z = 35 - 17 = 18\); electrons \(= 17 + 1 = 18\) (due to \(-1\) charge).
For \(^{37}\text{Cl}^-\): mass number \(A = 37\), neutrons \(= 37 - 17 = 20\); electrons \(= 17 + 1 = 18\).
Atomic mass units (amu) are related to mass number, so \(^{35}\text{Cl}^-\) has ~35 amu, \(^{37}\text{Cl}^-\) has ~37 amu.

Step2: Evaluate each option

• Neutrons: \(18

eq 20\) → no.

• Atomic mass units: \(35

eq 37\) → no.

• Protons: both have 17 → yes.
• Electrons: both have 18 → yes.

Mendeleev’s periodic table’s genius characteristic was leaving gaps for undiscovered elements (he predicted their properties). Arrangement by atomic mass was done by others, arrangement by properties is general, arrangement by atomic number is Moseley’s contribution.

Answer:

protons, electrons (the checkboxes for "protons" and "electrons" should be selected)

Question 6 (Multiple Choice)