Question

1. calcium ions play an important role in the function of neurons in the brain. elements that are chemically similar to calcium can interfere with the function of neutrons. which of the following is most likely to imitate calcium’s role in the function of neutrons?

a. sodium
c. strontium
b. potassium
d. rubidium

1. when the noble gases were first discovered, argon was placed with the noble gases in mendeleev’s periodic table, and potassium was placed with the alkali metals. how did this contradict mendeleev’s overall principle behind the organization of his periodic table?

a. argon has a higher atomic mass than potassium
c. argon has similar physical properties with the other noble gases
b. potassium has a higher atomic number than argon
d. potassium has similar chemical properties with the other alkali metals

1. according to the periodic table, which group do chlorine and iodine belong to?

a. alkali metals
c. alkaline earth metals
b. halogens
d. noble gasses

1. within a group of elements, as the atomic number increases, the atomic radius _______.

a. remains approximately constant
c. decreases
b. increases
d. increases and then quickly decreases

1. who updated the periodic table by arranging elements according to atomic number?

a. john dalton
c. dmitri mendeleev
b. j.j. thomson
d. henry moseley

1. arsenic belongs to group 15. how many electrons does arsenic have in its outermost enery level (valence electrons)?

Explanation:

Question 10

Elements in the same group of the periodic table have similar chemical properties. Calcium is in Group 2 (Alkaline Earth Metals). Strontium (Sr) is also in Group 2, so it has similar chemical properties to calcium and can imitate its role. Sodium (Group 1), Potassium (Group 1), and Rubidium (Group 1) are in a different group with different chemical properties.

Mendeleev's periodic table was originally arranged by atomic mass. Argon (atomic mass ~39.95) has a higher atomic mass than Potassium (atomic mass ~39.10), but Argon is a noble gas (Group 18) and Potassium is an alkali metal (Group 1). This contradicts the idea of arranging by atomic mass since a heavier element (Argon) was placed before a lighter one (Potassium) when considering their groups. Option b is about atomic number (not Mendeleev's original principle), c is about physical properties (Mendeleev focused on chemical properties and atomic mass), and d is a correct statement about Potassium's properties but not a contradiction.

Chlorine (Cl) and Iodine (I) are in Group 17 of the periodic table, which is the Halogens group. Alkali Metals are Group 1, Alkaline Earth Metals are Group 2, and Noble Gases are Group 18.

Answer:

c. Strontium

Question 11