Ch.2 - Atoms & ElementsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds
Sections
The Atom
Subatomic Particles
Isotopes
Ions
Atomic Mass
Periodic Table: Classifications
Periodic Table: Group Names
Periodic Table: Representative Elements & Transition Metals
Periodic Table: Element Symbols
Periodic Table: Elemental Forms
Periodic Table: Phases
Periodic Table: Charges
Calculating Molar Mass
Mole Concept
Law of Conservation of Mass
Law of Definite Proportions
Atomic Theory
Law of Multiple Proportions
Millikan Oil Drop Experiment
Rutherford Gold Foil Experiment
Additional Practice
Thomson's Cathode Ray Tube Experiment
The Chadwick Neutron Experiment
Mass Spectrometry
Additional Guides
Periodic table Charges (ignore)
Calculating Molar Mass (ignore)
Calculating Grams to Moles
LearnAdditional Practice
Next SectionIsotopes

The atom is composed of 3 subatomic particles: neutrons, protons, and electrons.

The Atom & Subatomic Particles

In terms of size, neutrons are the largest, protons are slightly smaller, and the electrons are the smallest.

Concept #1: The 3 subatomic particles share key differences and similarities in their masses and charges.  

Example #1: Osmium, one of the densest elements on earth, has an actual mass of 190.23 grams. According to the table above, what is its value in terms of atomic mass units?

Practice: According to the table above, how many electrons are required to produce a charge of –2.0 C?

Practice: If the charge and mass of one proton is 1.60218 x 10-19 C and 1.673 x 10-30 g respectively, what is the charge of 378 kg of protons?

Previous SectionThe Atom
Next SectionIsotopes
Additional Problems
What is the molar mass (g/mol) of a sample of aluminum where all the atoms have 15 neutrons? a. 13 b. 15 c. 28 d. 32 e. none of these
How many protons are there in a gold (Au) nucleus? a. 40 b. 55 c. 61 d. 79 e. 187
What is the name of the atom that has the atomic number 36?   a. chloride b. chlorine c. chromium d. krypton e. kryptonite
Identify the following element: a halogen whose anion contains 36 electrons.                   A. Cl                 B. Kr                 C. Rb                 D. Br
Which of the following statements is/are TRUE about subatomic particles? a) An anion has the same number of protons and electrons. b) Neutrons have the same mass as electrons. c) Protons and electrons have opposite, but equal in magnitude, charges. d) Neutrons and electrons are found in the nucleus. 
Which statement concerning the structure of the atom is correct? A. Protons and neutrons have most of the mass and occupy most of the volume of the atom. B. Electrons have most of the mass but occupy most of the volume C. Electrons have most of the mass but occupy very little of the volume of the atom D. Protons and neutrons have most of the mass but occupy very little of the volume of the atom.
Which statements about subatomic particles are true? a. If an atom has an equal number of protons and electrons, it will be charge-neutral. b. Electrons are attracted to protons.  c. Electrons are much lighter than neutrons. d. Protons have twice the mass of neutrons.   
The mass of a neutron is equal to the mass of a proton plus the mass of an electron. (T/F)
All neutral atoms of tin have 50 protons and 50 electrons. (T/F)
Determine the number of protons, neutrons and electrons in the following: A) p+= 18 n° = 22 e- = 40 B) p+= 40 n° = 22 e- = 18 C) p+= 18 n° = 22 e- = 18 D) p+= 18 n° = 18 e- = 2 E) p+= 22 n° = 18 e- = 18
Consider each of the following statements:             I.    An electron has a lower mass than a proton             II.  Electrons are found inside the nucleus of an atom             III. A neutral atom will have the same number of electrons as neutrons Which answer lists all of the true statements above?             A. I only         B. II only        C. I and II        D. I and III      E. All three are true  
Identify the charges of the protons, neutrons, and electrons. A) protons +1, neutrons 0, electrons -1 B) protons 0, neutrons -1, electrons +1 C) protons -1, neutrons 0, electrons +1 D) protons 0, neutrons +1, electrons -1 E) protons +1, neutrons -1, electrons 0
Which of the following statements is TRUE? (A) atoms contain equal numbers of protons and neutrons (B) the mass of an atom is equal to the number of protons + the number of electrons (C) neutrons have a mass of 0 and a charge of 1 (D) to calculate the number of neutrons in an atom, use the mass in the periodic table (E) the atomic number is the number of electrons in an atom
Which of the following statements about subatomic particles is TRUE?A) A neutral atom contains the same number of protons and electrons.B) Protons have about the same mass as electrons.C) Electrons make up most of the mass of an atom.D) Protons and neutrons have opposite, but equal in magnitude, charges.E) Neutrons and electrons are found in the nucleus of an atom.
In all the neutral atoms, there are equal numbers of(A) neutrons and electrons(B) electrons and protons(C) protons and neutrons
Which statement concerning the structure of the atom is correct?(A) Protons and neutrons have most of the mass and occupy most of the volume of the atom.(B) Protons and neutrons have most of the mass but occupy very little of the volume of the atom.(C) Electrons have most of the mass and occupy most of the volume of the atom.(D) Electrons have most of the mass but occupy very little of the volume of the atom.
What is the number of neutrons in Cl-1737?(A) 17(B) 20(C) 21(D) 37
Which statement is true?(A) The atomic number of an element is the number of protons in one atom.(B) The nucleus of an atom contains neutrons and electrons.(C) The number of electrons outside the nucleus is the same as the number of the neutrons in the nucleus.(D) The mass number of an atom is the number of protons in the nucleus plus the number of electrons outside.
How many electrons are necessary to produce a charge of - 1.0 C? What is the mass of this many electrons? 
How many electrons would it take to equal the mass of a proton? 
Determine whether the following statement is true or false. If false, correct the statement to make it true: (c) The number of electrons in an atom equals the number of neutrons in the atom.
How many protons, neutrons, and electrons are in the following atom: (a) 40Ar
How many protons, neutrons, and electrons are in the following atom: (b) 65Zn
How many protons, neutrons, and electrons are in the following atom: 70Ga
How many protons, neutrons, and electrons are in the following atom: (d) 80Br
Write the symbol of each atom using the  AZX format.
Write the symbol of each atom using the  AZX format.
How many protons, neutrons, and electrons are in each of the following atoms or ions?a. 2412Mg
How many protons, neutrons, and electrons are in each of the following atoms or ions?e. 5927Co
How many protons, neutrons, and electrons are in each of the following atoms or ions?f. 7934Se
How many protons, neutrons, and electrons are in each of the following atoms or ions?h. 6328Ni
Identify each of the following elements:a. a member of the same family as oxygen whose most stable ion contains 54 electrons
Identify each of the following elements:b. a member of the alkali metal family whose most stable ion contains 36 electrons
Identify each of the following elements:c. a noble gas with 18 protons in the nucleus
An iron-56 nucleus contains      A) 56 protons and 56 neutrons. B) 26 protons and 30 neutrons. C) 56 protons and 26 neutrons. D) 30 protons and 26 neutrons. E) 26 protons and 26 neutrons.
Determine the number of protons, neutrons and electrons in the following:   4018X A) p+ = 18       n° = 22             e- = 40 B) p+ = 22       n° = 18             e- = 18 C) p+ = 40       n° = 22             e- = 18 D) p+ = 18       n° = 22             e- = 18 E) p+ = 18       n° = 18             e- = 22  
The atomic number indicates __________.   A) the total number of neutrons and protons in a nucleus B) the number of neutrons in a nucleus C) the number of protons or electrons in a neutral atom D) the number of atoms in 1 g of an element E) the number of different isotopes of an element
What is the identity of element Q if the ion Q 2+ contains 10 electrons?       A) Ne              B) O                 C) Mg              D) C
What does "X" represent in the following symbol?a. mercuryb. chlorinec. scandiumd. brominee. selenium
How many neutrons are there in an atom of lead whose mass is 208 amu?a. 290b. 126c. 208d. 82e. 145
Consider an atom of osmium-190 (190Os). It has:(A) 76 protons, 190 neutrons, 76 electrons(B) 76 protons, 76 neutrons, 114 electrons(C) 76 protons, 114 neutrons, 76 electrons(D) 114 protons, 76 neutrons, 114 electrons(E) 76 protons, 76 neutrons, 76 electrons
How many protons, electrons and neutrons are there in the cation formed from an atom of magnesium that has a mass of 24?(A) 12 protons, 12 electrons, 12 neutrons(B) 12 protons, 10 electrons, 14 neutrons(C) 12 protons, 10 electrons, 12 neutrons(D) 14 protons, 12 electrons, 10 neutrons(E) 10 protons, 12 electrons, 12 neutrons
A proton weighs 1.007276 amu, a neutron weighs 1.008665 amu, and an electron weighs 5.486 × 10−4 amu.What is the expected mass of a beryllium-9 nucleus, based on the total mass of its protons and neutrons? Express your answer in atomic mass units using seven significant figures.
Specify the number of protons, neutrons, and electrons in the neutral atom iron-56. Enter your answers as integers separated by commas. 
What is the name of the element that has atomic number 59?a) Princeiumb) Promethiumc) Praseodymiumd) Proctoriume) Protactinium
The atomic number of an atom of  80Br is _____. (a) 115 (b) 35 (c) 45 (d) 73 (e) 80
The atomic number of oxygen is 8. What is the mass number of a oxygen atom with 7 neutrons?
A sulfur atom has a mass of 34 amu. How many neutrons does it have?a) 16b) 17c) 18d) 32e) 34