CHEM 98 Atoms and the Periodic Table

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Questions and Answers

What is the atomic weight calculated by?

Weighted average mass of the element’s isotopes (correct)

Fixed mass values of each isotope

Total mass of all isotopes combined

Sum of the isotopic masses only

What percentage of gallium is Ga-71?

39.6% (correct)

60.4%

30.0%

70.0%

In which part of the periodic table do metals typically occur?

Right side

Center

Bottom

Left side (correct)

Which of the following is true about nonmetals?

They are found on the upper-right side of the periodic table. Signup and view all the answers

What does the mass number indicate?

Total number of protons and neutrons Signup and view all the answers

Who is credited with producing the forerunner of the modern periodic table?

Dmitri Mendeleev Signup and view all the answers

How is atomic weight calculated based on isotopes?

It is computed using the formula Σ[(isotopic abundance) × (isotopic mass)]. Signup and view all the answers

What characteristic commonly describes metals?

Good conductors of heat and electricity Signup and view all the answers

Which statement about atoms is true?

Atoms are the smallest particle that can be divided and still identified as an element. Signup and view all the answers

What is the significance of the atomic number?

It indicates the number of protons in the atoms of a given element. Signup and view all the answers

Which statement describes the mass of subatomic particles accurately?

Protons and neutrons have similar masses, while electrons are significantly lighter. Signup and view all the answers

What does the term 'atomic mass unit' (amu) refer to?

A mass unit based on the mass of a carbon-12 atom. Signup and view all the answers

Which of the following best describes the composition of an atom's nucleus?

It contains protons and neutrons and is dense. Signup and view all the answers

Which principle is NOT part of atomic theory?

Atoms can be divided into smaller particles while retaining their identity. Signup and view all the answers

What happens to electrons in relation to the nucleus of an atom?

They move rapidly in the space surrounding the nucleus due to attraction to the protons. Signup and view all the answers

Which of these statements about electron configurations is accurate?

Electron configurations influence the chemical properties of atoms. Signup and view all the answers

What is the mass number of an atom if it contains 15 protons and 16 neutrons?

31 Signup and view all the answers

Which of the following statements about isotopes is true?

Isotopes have the same number of protons and different mass numbers. Signup and view all the answers

How many neutrons are present in a chlorine-35 atom?

18 Signup and view all the answers

If an atom has an atomic number (Z) of 28 and a mass number (A) of 60, how many electrons does it have?

28 Signup and view all the answers

What is the number of neutrons in a phosphorus atom with a mass number of 31 and atomic number of 15?

16 Signup and view all the answers

Which element has an atomic number of 17?

Chlorine Signup and view all the answers

How is a specific isotope represented in chemical notation?

Atomic number as a subscript and mass number as a superscript. Signup and view all the answers

If sodium has 11 protons, what is the mass number of its most common isotope?

23 Signup and view all the answers

Study Notes

Atomic Theory and Structure of Atoms

Atoms are the smallest identifiable particles of elements, derived from the Greek word "atomos" meaning "indivisible."
Atomic theory is based on four main assumptions:
- All matter is composed of atoms.
- Atoms of one element differ from those of others.
- Chemical compounds consist of atoms combined in specific ratios.
- Chemical reactions alter the arrangements of atoms, not the atoms themselves.
Atoms consist of protons (positively charged), neutrons (neutral), and electrons (negatively charged), with protons and neutrons forming the dense nucleus and electrons moving in the surrounding space.
The mass of an atom is expressed in atomic mass units (amu), with one amu based on the mass of a carbon-12 atom.

Elements and Atomic Number

Atomic number (Z) indicates the number of protons in an atom; e.g., Sodium (Na) has Z = 11, Magnesium (Mg) has Z = 12.
Mass number (A) is the total of protons and neutrons in an atom; can be calculated as A = Z + number of neutrons.
In neutral atoms, the number of protons equals the number of electrons, maintaining overall electrical neutrality.
Example of phosphorus: Z = 15 and A = 31 gives 15 protons, 15 electrons, and 16 neutrons.

Isotopes and Atomic Weight

Isotopes are atoms with the same atomic number but different mass numbers due to varying neutron counts.
Example: Chlorine-35 and Chlorine-37 both have Z = 17 but differ in A (35 and 37, respectively).
Isotopes of hydrogen include protium, deuterium, and tritium.
Atomic weight represents the average mass of an element’s isotopes, weighted by their natural abundance.
Atomic weight calculation: Atomic weight = Σ[(isotopic abundance) × (isotopic mass)].

The Periodic Table

The periodic table organizes all known elements, displaying their symbols, names, and atomic masses.
Dmitri Mendeleev created an early version of the periodic table, arranging elements by their properties and atomic weights.
Elements are classified based on physical and chemical properties:
- Metals are malleable, lustrous, and good conductors, found on the left side of the table.
- Nonmetals are poor conductors and located on the upper-right side of the table.

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Description

This quiz covers Chapter 2 of 'Fundamentals of General, Organic, and Biological Chemistry', focusing on atomic theory, elements, isotopes, and the periodic table. Test your understanding of atomic structure and electron configurations.