Question 1

Which of the following statements best describes the atomic theory as proposed in modern chemistry?

Accepted Answer

Chemical reactions change only the way atoms are combined in compounds, not the atoms themselves.

Question 2

Given the isotope symbol $$\ ^{12}_{6}\mathrm{C} $$ shown in the image, how many neutrons does this atom have?

Accepted Answer

6

Question 3

Which subatomic particle has a mass approximately $$1/1836$$ that of a proton and carries a negative charge?

Accepted Answer

Electron

Question 4

What is the electron configuration for magnesium (Mg), atomic number 12?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$

Question 5

Which group of elements is characterized by being shiny, soft metals with low melting points and high reactivity with water?

Accepted Answer

Alkali metals (Group 1A)

Question 6

How many electrons can the third shell of an atom hold?

Accepted Answer

18

Question 7

Which of the following best describes the shape of p orbitals?

Accepted Answer

Dumbbell-shaped

Question 8

A neutral atom of phosphorus (atomic number 15) has a mass number of 31. How many neutrons does it contain?

Accepted Answer

16

Question 9

Which of the following is the correct shorthand electron configuration for sodium (Na)?

Accepted Answer

$$[Ne]\ 3s^1$

Question 10

What is the general valence-shell electron configuration for elements in group 6A?

Accepted Answer

$$ns^2np^4$

Question 11

Which element is represented by the electron configuration $$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^3$$?

Accepted Answer

Phosphorus (P)

Question 12

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes have identical atomic numbers but different mass numbers.

Question 13

What is the atomic weight of gallium if 60.4% is $$^{69}Ga ($$mass = 68.9257 amu) and 39.6% is $$^{71}Ga ($$mass = 70.9248 amu)?

Accepted Answer

$$69.8\ \mathrm{amu}$$

Question 14

Which block of the periodic table contains elements whose last electron enters an f orbital?

Accepted Answer

f block

Question 15

Which of the following elements is a metalloid?

Accepted Answer

Silicon (Si)

Question 16

How many valence electrons does tin (Sn, atomic number 50) have, and what is its valence-shell configuration?

Accepted Answer

4 valence electrons; $$5s^2$$\ $$5p^2$$

Question 17

Which of the following is the correct electron-dot symbol for an element in group 5A?

Accepted Answer

The symbol with five dots arranged around it

Question 18

Which rule states that two or more orbitals with the same energy are each half-filled by one electron before any one orbital is completely filled?

Accepted Answer

Hund's rule

Question 19

Which element has the electron configuration $$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^6$$\ $$4s^2$$\ $$3d^{10}$$\ $$4p^6$$\ $$5s^2$$\ $$4d^2$$?

Accepted Answer

Zirconium (Zr)

Question 20

Which of the following elements is most likely to be found in nature only in combination with other elements, such as in table salt?

Accepted Answer

Chlorine (Cl)

Atoms and the Periodic Table: Structured Study Notes

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