The Structure of the Atom
Big Idea
The first theories of the "atom" were developed by two 5th-century BC Greek philosophers: Leucippus of Miletus (an ancient Greek city in what is now Turkey) and Democritus of Abdera (in the region of modern Thrace, Greece). Their concepts of atomism were not especially experimental in origin, however they were correct in their reasoning that if you could examine matter on ever smaller scales (which was beyond their ability - well before the invention of the microscope) then eventually you could see individual atoms - the smallest particle of matter that could not be divided further. Leucippus and Democritus reasoned that the different physical properties of matter - such as color, hardness, etc. - could be explained by the different shapes and/or arrangements of atoms in the material.
The first theories of the "atom" were developed by two 5th-century BC Greek philosophers: Leucippus of Miletus (an ancient Greek city in what is now Turkey) and Democritus of Abdera (in the region of modern Thrace, Greece). Their concepts of atomism were not especially experimental in origin, however they were correct in their reasoning that if you could examine matter on ever smaller scales (which was beyond their ability - well before the invention of the microscope) then eventually you could see individual atoms - the smallest particle of matter that could not be divided further. Leucippus and Democritus reasoned that the different physical properties of matter - such as color, hardness, etc. - could be explained by the different shapes and/or arrangements of atoms in the material.
Supplemental Readings
An Introduction to Chemistry: Ch.3 - The Structure of Matter and the Chemical Elements Section 3.2 thru Section 3.4: pages 80 - 94
Videos
Basic Atomic Structure: A Look Inside the Atom by Tyler DeWitt [7:44]
What does the inside of an atom look like? Here, we'll look at the subatomic particles ( protons, neutrons, and electrons) that make up the atom. We'll see how the electrons orbit the nucleus, and talk about the masses of protons, neutrons, and electrons in amu, or atomic mass unit.
What's the Difference between an Atom and a Molecule? by Tyler DeWitt [5:16]
Never be confused by this concept again! In this video, we talk about the difference between an atom and molecule, and discuss the nucleus, energy levels, protons and neutrons, compounds, covalent bonding, sharing electrons, and lego blocks.
Atomic Number, Mass Number, and Net Charge by Tyler DeWitt [6:26]
How do you calculate and determine atomic number, mass number, and net charge? Atomic number is the number of protons in an atom. Mass number is the number of neutrons in an atom, and net charge describes how the protons and electrons balance out.
What's an Ion? by Tyler DeWitt [6:52]
Confused about ions? We'll learn the difference between an atom and an ion. Ions are formed because of a net charge on an atom, because the number of protons and electrons do not balance. This means that the atom is no longer electrically neutral, but is a cation or an anion. We also talk about polyatomic ions.
Practice Problems: Net Charge, Mass Number, Atomic Number by Tyler DeWitt [4:56]
Practice and example problems to help you learn how to determine and calculate the net charge, mass number, and atomic number of atoms. Also we'll look at how to determine the number of protons, neutrons, and electrons in an atom.
What are Isotopes? by Tyler DeWitt [7:56]
We'll learn about what isotopes are and how to write atomic number and mass number in isotope notation. We talk about a simple analogy with cars to explain this tutorial. Isotopes are versions of an atom or an element that have the same number of protons, but different numbers of neutrons. Isotopes and isotope notation are particularly important in nuclear chemistry.
Isotope Notation by Tyler DeWitt [7:56]Learn how to write atoms in isotope notation! In isotope notation, you can quickly show how many protons, neutrons, and electrons are in an atom. You put the atomic number, mass number, and net charge around the chemical element symbol. Isotope notation is particularly important in nuclear chemistry, because if you're doing fission, fusion, alpha decay, beta decay, positron emission, or electron capture, you want to be able to tell how many neutrons and protons are in the nucleus.
Isotopes and Elements Practice Problems by Tyler DeWitt [12:49]In this video we'll look at how to determine, calculate and solve for atomic number, mass number, isotopes, net charge, protons, neutrons, and electrons. We'll determine what element an atom is by using the periodic table.
Additional Resources
Animations/Simulations
Atomic Symbols, Atomic Numbers, and Mass Numbers by Wisc-Online
Ions by Wisc-Online
Isotopes by Wisc-Online
Build an Atom by PhET - University of Colorado
Additional Advanced Video
History of the Atom by BozemanScience [9:09]
An Introduction to Chemistry: Ch.3 - The Structure of Matter and the Chemical Elements Section 3.2 thru Section 3.4: pages 80 - 94
Videos
Basic Atomic Structure: A Look Inside the Atom by Tyler DeWitt [7:44]
What does the inside of an atom look like? Here, we'll look at the subatomic particles ( protons, neutrons, and electrons) that make up the atom. We'll see how the electrons orbit the nucleus, and talk about the masses of protons, neutrons, and electrons in amu, or atomic mass unit.
What's the Difference between an Atom and a Molecule? by Tyler DeWitt [5:16]
Never be confused by this concept again! In this video, we talk about the difference between an atom and molecule, and discuss the nucleus, energy levels, protons and neutrons, compounds, covalent bonding, sharing electrons, and lego blocks.
Atomic Number, Mass Number, and Net Charge by Tyler DeWitt [6:26]
How do you calculate and determine atomic number, mass number, and net charge? Atomic number is the number of protons in an atom. Mass number is the number of neutrons in an atom, and net charge describes how the protons and electrons balance out.
What's an Ion? by Tyler DeWitt [6:52]
Confused about ions? We'll learn the difference between an atom and an ion. Ions are formed because of a net charge on an atom, because the number of protons and electrons do not balance. This means that the atom is no longer electrically neutral, but is a cation or an anion. We also talk about polyatomic ions.
Practice Problems: Net Charge, Mass Number, Atomic Number by Tyler DeWitt [4:56]
Practice and example problems to help you learn how to determine and calculate the net charge, mass number, and atomic number of atoms. Also we'll look at how to determine the number of protons, neutrons, and electrons in an atom.
What are Isotopes? by Tyler DeWitt [7:56]
We'll learn about what isotopes are and how to write atomic number and mass number in isotope notation. We talk about a simple analogy with cars to explain this tutorial. Isotopes are versions of an atom or an element that have the same number of protons, but different numbers of neutrons. Isotopes and isotope notation are particularly important in nuclear chemistry.
Isotope Notation by Tyler DeWitt [7:56]Learn how to write atoms in isotope notation! In isotope notation, you can quickly show how many protons, neutrons, and electrons are in an atom. You put the atomic number, mass number, and net charge around the chemical element symbol. Isotope notation is particularly important in nuclear chemistry, because if you're doing fission, fusion, alpha decay, beta decay, positron emission, or electron capture, you want to be able to tell how many neutrons and protons are in the nucleus.
Isotopes and Elements Practice Problems by Tyler DeWitt [12:49]In this video we'll look at how to determine, calculate and solve for atomic number, mass number, isotopes, net charge, protons, neutrons, and electrons. We'll determine what element an atom is by using the periodic table.
Additional Resources
Animations/Simulations
Atomic Symbols, Atomic Numbers, and Mass Numbers by Wisc-Online
Ions by Wisc-Online
Isotopes by Wisc-Online
Build an Atom by PhET - University of Colorado
Additional Advanced Video
History of the Atom by BozemanScience [9:09]