Unit One Atomic Structure & Theory (part 1)

Questions and Answers

What is the symbol for a proton?

p^+

Where is the proton located in an atom?

nucleus

What is the charge of a proton?

1+ (correct)

neutral

What is the mass of a proton?

1.673 x 10^-24 Signup and view all the answers

What is the symbol for a neutron?

n^0 Signup and view all the answers

Where is the neutron located in an atom?

nucleus Signup and view all the answers

What is the charge of a neutron?

none Signup and view all the answers

What is the mass of a neutron?

1.673 x 10^-24 Signup and view all the answers

What is the symbol for an electron?

e^- Signup and view all the answers

Where is the electron located in an atom?

electron cloud Signup and view all the answers

What is the charge of an electron?

1- Signup and view all the answers

What is the mass of an electron?

9.11 x 10^-28 Signup and view all the answers

The mass of the atom is due to the and the .

Protons, Neutrons Signup and view all the answers

The volume of the atom is due to the __________.

Electron cloud Signup and view all the answers

What does the atomic number represent?

Number of protons in an atom Signup and view all the answers

What does it mean when an atom is neutral?

Number of protons = number of electrons Signup and view all the answers

How many protons and electrons does a neutral atom of sodium contain?

11 protons, 11 electrons Signup and view all the answers

How many protons and electrons does a positive atom of potassium (K^+) contain?

20 protons, 19 electrons Signup and view all the answers

How many protons and electrons does a negative atom of chlorine (Cl^-) contain?

17 protons, 18 electrons Signup and view all the answers

How many protons and electrons does an atom of oxygen with a negative 2 charge (O^2-) contain?

8 protons, 10 electrons Signup and view all the answers

How to determine the composition of an atom?

Know the mass number and atomic number Signup and view all the answers

How do you calculate the number of neutrons in an atom?

Mass number - Atomic number Signup and view all the answers

A neutral atom of magnesium has a mass number of 24. How many protons, neutrons, and electrons does it contain?

12 protons, 12 neutrons, 12 electrons Signup and view all the answers

An ion of zinc with a positive 4 charge has a mass number of 65. How many protons, neutrons, and electrons does it contain?

30 protons, 35 neutrons, 26 electrons Signup and view all the answers

What are isotopes?

Atoms of the same element having different numbers of neutrons. Signup and view all the answers

The two ways to represent composition are and .

Isotopic Notation, Name and number method Signup and view all the answers

What is isotopic notation?

Mass number and atomic number Signup and view all the answers

What is the name and number method?

Carbon-18 Signup and view all the answers

What is the charge on a certain ion with atomic number 16, mass number 33, and 18 electrons?

2- Signup and view all the answers

What is the identity of an ion with atomic number 16?

Sulfur Signup and view all the answers

How many neutrons does the nucleus of an ion with atomic number 16 and mass number 33 have?

17 Signup and view all the answers

How many protons does tritium (an isotope of hydrogen) have?

1 proton Signup and view all the answers

What is the mass number of tritium?

3 amu Signup and view all the answers

What is the charge on a magnesium ion that has 10 electrons?

2+ Signup and view all the answers

How many neutrons are there in a chromium atom with a mass number of 54?

30 Signup and view all the answers

Substance E has 29 protons, 28 electrons, and 34 neutrons. Substance F has 29 protons, 27 electrons, and 34 neutrons. What can E and F be categorized as?

Ions Signup and view all the answers

What element has 38 protons and 45 neutrons?

Strontium (Sr) Signup and view all the answers

What is atomic mass?

Weighted average of all the isotopes for a given element Signup and view all the answers

How should atomic mass be represented on the periodic table?

Decimal number Signup and view all the answers

How can abundance of isotopes be determined?

Closest mass to atomic mass Signup and view all the answers

What is the formula for mass number?

Number of neutrons + Atomic number Signup and view all the answers

What is the average atomic mass of an element that has isotopes of 49.9461 amu, 51.9405 amu, 52.9407 amu, and 53.9389 amu with respective abundances?

51.995 amu Signup and view all the answers

What is the identity of the element with average atomic mass of 51.995?

Chromium (Cr) Signup and view all the answers

Calcium has isotopes with masses of 35 amu, 41 amu, and 40 amu. Which isotope is the most abundant?

40 amu Signup and view all the answers

What is the average atomic mass of atom X with various isotopes?

42.13 amu Signup and view all the answers

Study Notes

Atomic Structure Components

Proton (p^+): Positively charged particle located in the nucleus; mass approximately 1.673 x 10^-24 grams.
Neutron (n^0): Neutral particle located in the nucleus; mass approximately 1.673 x 10^-24 grams.
Electron (e^-): Negatively charged particle found in the electron cloud; mass approximately 9.11 x 10^-28 grams.

Atomic Properties

Mass of an atom is attributed to protons and neutrons.
Volume of an atom is determined by the electron cloud.

Atomic Number and Charge

Atomic Number: Represents the number of protons in an atom; defines the element and dictates the arrangement of elements on the periodic table.
Atoms are neutral when protons equal electrons. Positive charge occurs when protons exceed electrons, and negative charge occurs when electrons exceed protons.

Example Calculations

Sodium (Na) has 11 protons and 11 electrons when neutral.
Potassium ion (K^+) has 20 protons and 19 electrons (one less due to a positive charge).
Chlorine ion (Cl^-) has 17 protons and 18 electrons (one more due to a negative charge).
Oxygen ion with a charge of -2 (O^2-) has 8 protons and 10 electrons.

Isotopes and Composition

Isotopes are variants of the same element differing in neutron count. All isotopes have the same atomic number.
- Examples:
  - Hydrogen-1: 1 proton, 0 neutrons
  - Hydrogen-2: 1 proton, 1 neutron
  - Hydrogen-3: 1 proton, 2 neutrons
Knowledge of mass number and atomic number enables determination of isotopic composition.
Number of neutrons calculated as: Mass number - Atomic number.

Elemental Examples

Magnesium (mass number 24): Contains 12 protons, 12 neutrons, and 12 electrons.
Zinc ion (Zn^4+) has 30 protons, 35 neutrons, and 26 electrons (4 electrons less).

Atomic Representation

Isotopic Notation: Indicates mass and atomic number, e.g., Oxygen-16 (16 O, 8).
Name and Number Method: E.g., Carbon-18 indicates mass number.

Average Atomic Mass and Abundance

Atomic mass is the weighted average of isotopes; it is not the same as mass number.
To determine abundance, identify the isotope nearest to the element's average atomic mass.

Calculation of Average Atomic Mass

For isotopes with varying percentages:
- Calculate average atomic mass using the formula:
  - (Mass1 * Abundance1) + (Mass2 * Abundance2) + ...

Additional Examples

Element with 38 protons and 45 neutrons identified as Strontium (Sr).
Most abundant isotopes typically have masses closest to the average atomic mass on the periodic table.

Additional Concepts in Atomic Structure

Ions: Atoms with unequal numbers of protons and electrons, categorized by charge (positive or negative).
Nuclides: Unique nuclear species characterized by proton and neutron counts.
Nucleons: General term for protons and neutrons within an atomic nucleus.

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