$$0.6010 \times 68.926 + 0.3990 \times 70.925 = 69.72$$ amu

$$\text{number of protons} = \text{number of electrons}$$

Question 1

Which of the following statements about elements is correct?

Accepted Answer

Elements are pure substances from which all other things are built.

Question 2

Which element is a metalloid according to its position on the periodic table?

Accepted Answer

Silicon (Si)

Question 3

A neutral atom of magnesium has an atomic number of 12 and a mass number of 24. How many neutrons does it have?

Accepted Answer

$$24 - 12 = 12$$ neutrons

Question 4

Which of the following elements is most likely to have electrons in the 3p sublevel?

Accepted Answer

Phosphorus (P)

Question 5

Which statement about the structure of the atom is FALSE?

Accepted Answer

A neutron has a negative charge.

Question 6

Which element has the largest atomic radius among the following?

Accepted Answer

Potassium (K)

Question 7

Which of the following is a correct statement about isotopes?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 8

A sample of gallium contains 60.10% $$^{69}Ga (68.926 $$amu) and 39.90% $$^{71}Ga (70.925 $$amu). What is the average atomic mass of gallium?

Accepted Answer

$$0.6010 	imes 68.926 + 0.3990 	imes 70.925 = 69.72$$ amu

Question 9

Which element has the highest ionization energy?

Accepted Answer

Neon (Ne)

Question 10

Which of the following is a property of metals?

Accepted Answer

They are shiny, ductile, and conduct heat and electricity.

Question 11

Which of the following elements is a noble gas?

Accepted Answer

Argon (Ar)

Question 12

How many unpaired electrons does a neutral fluorine (F) atom have?

Accepted Answer

One

Question 13

Which of the following best describes the Pauli exclusion principle?

Accepted Answer

Each orbital can hold a maximum of two electrons with opposite spins.

Question 14

Which of the following elements is in Group 1A (alkali metals)?

Accepted Answer

Potassium (K)

Question 15

Which of the following statements about electromagnetic radiation is correct?

Accepted Answer

High-energy radiation has short wavelengths.

Question 16

Which of the following is the correct electron configuration for chlorine (Cl)?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^5$$

Question 17

Which of the following elements has the greatest metallic character?

Accepted Answer

Cesium (Cs)

Question 18

Which of the following is the correct relationship for a neutral atom?

Accepted Answer

$$	ext{number of protons} = 	ext{number of electrons}$$

Question 19

Which of the following is NOT a feature of Dalton’s atomic theory?

Accepted Answer

Atoms can be divided into protons, neutrons, and electrons.

Atoms and Elements: Structure, Properties, and the Periodic Table

Guida di studio - Domande di pratica