Atomic Number Reading 2

Each element has a unique number of _____, which is called the atomic number. For an electrically neutral atom, this number is also equal to the number of _____ present.

Blank 1: protons Blank 2: electrons

Each element can be represented by an atomic symbol with the format (A/Z)(X) . Match each component of this symbol with its correct meaning. A Atomic number: the number of protons in the nucleus Z Mass number: the total number of protons and neutrons in the nucleus X Atomic symbol: the element symbol found in the periodic table

Z: Atomic number: the number of protons in the nucleus A: Mass number: the total number of protons and neutrons in the nucleus X: Atomic symbol: the element symbol found in the periodic table

Which of the following correctly defines the average atomic mass of an element? a. The average of the masses of that element's naturally occurring isotopes weighted according to their abundance b. The average number of neutrons of the isotopes of an element c. The sum of the element's protons and neutrons as they occur naturally d. The sum of the element's isotopes e. The sum of atomic masses of all isotopes of an element divided by the number of different isotopes.

a. The average of the masses of that element's naturally occurring isotopes weighted according to their abundance

Select all that apply A particular atom of an element is represented by the symbol (15/7)N Which of the following options correctly interpret this symbol? Select all that apply. a. The element contains 7 protons in its nucleus. b. The atomic number of the element is 15. c. The element contains 8 neutrons in its nucleus. d. The element has 15 electrons.

a. The element contains 7 protons in its nucleus. c. The element contains 8 neutrons in its nucleus.

Select all that apply Which of the following options correctly describe the mass number of an element? Select all that apply. Multiple select question. a. The mass number is often written as a left superscript next to the atomic symbol. b. The mass number of an element is given the symbol A. c. In a neutral atom, the mass number equals the number of electrons in the atom. d. The mass number of a particular element never varies. e. The mass number is given by the sum of the protons and neutrons in the nucleus.

a. The mass number is often written as a left superscript next to the atomic symbol. b. The mass number of an element is given the symbol A. e. The mass number is given by the sum of the protons and neutrons in the nucleus.

Isotopes are atoms of the same element that have the same _____ number but a different _____ number. This is because isotopes have the same number of protons but a different number of _____. a. atomic; mass; neutrons b. mass; atomic; electrons c. mass; atomic; neutrons d. atomic; mass; protons

a. atomic; mass; neutrons

An unknown element has two isotopes: one whose mass is 114.998 amu (25.00% abundance) and the other whose mass is 117.986 amu (75.00% abundance). The average atomic mass of the element is equal to _____. a. 116.50 b. 117.24 c. 115.74 d. 118.002

b. 117.24 Reason: (114.998 × 0.2500) + (117.996 × 0.7500) = (28.75 + 88.49) = 117.24

Which of the following options correctly describe isotopes? Select all that apply. a. Isotopes are atoms of the same element with the same mass. b. Isotopes have different numbers of neutrons. c. Isotopes have different numbers of protons. d. Isotopes have similar chemical properties. e. Isotopes of the same element have the same element symbols.

b. Isotopes have different numbers of neutrons. d. Isotopes have similar chemical properties. e. Isotopes of the same element have the same element symbols.

Which of the following statements correctly describe the atomic number of an element? Select all that apply. a. The atomic number is represented by the symbol A. b. The atomic number is equal to the number of protons in the nucleus. c. The atomic number of an element varies depending on the number of electrons present. d. Each element has its own unique atomic number. e. The atomic number equals the number of neutrons present in the atom.

b. The atomic number is equal to the number of protons in the nucleus. d. Each element has its own unique atomic number.

Select all that apply Which of the components of the atomic symbol format (A on top of Z)(X besides this) can be used alone to determine the identity of an element? Select all that apply. Multiple select question. a. A b. X c. Z

b. x c. z

Select the atomic symbol that correctly represents an atom of nickel with 28 protons and 30 neutrons in its nucleus. Multiple choice question. a. (58/30)Ni b. (28/58)Ni c. (58/28)Ni d. (30/28)Ni

c. (58/28)Ni

An unknown element has two isotopes: one whose mass is 68.926 amu (60.00% abundance) and the other whose mass is 70.925 amu (40.00% abundance). The average atomic mass of the element is equal to _____. a. 70.13 b. 69.93 c. 69.73 d. 139.85

c. 69.73

Select all that apply It is common to represent an element using the atomic symbol format (a/z)(X). Select all the statements that correctly identify the components of this abbreviation. a. Z indicates the number of neutrons in the nucleus of the element. b. The sum of protons and electrons is given by Z. c. A indicates the mass number of the element. d. The sum of protons and neutrons is given by A.

c. A indicates the mass number of the element. d. The sum of protons and neutrons is given by A.

How does the average atomic mass of an element compare to the mass number? a. The average atomic mass of an element is the same as its mass number. b. The average atomic mass is equal to the mass number of the most abundant isotope of an element. c. The average atomic mass is the average mass of a mixture of isotopes, whereas each isotope has its own mass number. d. The average atomic mass includes the mass of the electrons, whereas the mass number depends only on the neutrons and protons.

c. The average atomic mass is the average mass of a mixture of isotopes, whereas each isotope has its own mass number.

The _____ number of an atom is equal to the sum of the protons and _____ in the nucleus of the atom. a. atomic; neutrons b. mass; electrons c. atomic; electrons d. mass; neutrons

d. mass; neutrons