Let’s Talk Chemistry! The atom

1. The Atom made up of protons, neutrons and electrons basic unit of matter, VERY small made up of protons, neutrons and electrons the atom is neutrally charged (no charge) The units used to measure the mass of the particles in an atom are the Atomic Mass Unit (amu) Simplest and most basic unit of matter Neutrally charged since they have the same number of protons and electrons Atomic number of two: Has two protons Must have two electrons because the charge is neutral Neutrons have no charge

Model of a Helium Atom: Atomic Number 2 proton neutron electron

2. Structure of an atom The nucleus of an atom: Protons are positively charged Mass is 1 amu Neutrons have no charge Electrons: in constant motion around nucleus found in the electron cloud negatively charged Mass is 1/1840 amu Atoms have an equal number of protons and electrons.

3. Elements 110 known elements Each element has its own unique number of protons The number of protons is known as the atomic number And… since the number of protons equals the number of electrons, you can use the atomic number to find the number of electrons as well!

But what about neutrons? Each element also has a certain number of neutrons To find the number of neutrons, you subtract the atomic number from the rounded atomic mass

Formulas! Atomic number = number of protons = number of electrons Number of neutrons = rounded atomic mass – atomic number More formulas! They are so helpful, I just want to remember them all!!

5. Isotopes Atoms that have the same number of protons but a different number of neutrons The mass number is the sum of the protons and neutrons in an isotope

Carbon isotope challenge For each example: How many protons, neutrons, electrons? Which ones are the isotopes?

Carbon isotope challenge isotopes

3. Elements on the periodic table Pure substance Made of one type of atom Represented by 1, 2 or 3 letters Number of protons in an atom is the atomic number (i.e. Carbon is 6, Oxygen is 8) Since number of protons equals the number of electrons, Carbon has 6 electrons, Oxygen has 8 electrons

4. History of the Periodic Table Mendeleev designed the first periodic table He arranged the elements by increasing atomic mass He left blank spaces according to similarities in columns of elements

More history… Mendeleev’s blank spaces (or predictions) were elements that he claimed were not discovered yet. As it turns out, he was right!! Scientists later discovered the missing elements with the properties that Mendeleev predicted!

And even more history! Moseley discovered the atomic number He organized the periodic table by increasing atomic number This allowed for elements with similar properties to fall into place An gave way to the modern periodic table

5. Molecules Smallest unit (part) of a compound Hydrogen molecule Explain organic molecule and inorganic molecule: Organic: Must contain Carbon and Hydrogen Inorganic: Does not contain Carbon and Hydrogen Some molecular compounds just contain Carbon, not considered to be organic Carbon dioxide is an example of an inorganic molecule containing carbon Diatomic molecule = two atoms joined together A compound can also be a molecule, but a molecule cannot be a compound

6. Compounds a substance that contains two or more different elements organic compounds must contain Carbon Compound two different elements (means two or more) Acetic acid

Shows how many atoms of each element a molecule contains 7. Molecular formula Shows how many atoms of each element a molecule contains Does not tell you about a molecule’s structure Water Glucose Ammonia

Examples of molecular formulas H2O 2 hydrogen 1 oxygen NH3 1 nitrogen 3 hydrogen C6H12O6 6 carbon 12 hydrogen 6 oxygen

8. Structural formula Shows how atoms are arranged in a molecule 2-dimensional representation of a molecule’s structure From structural formulas, scientists can create ball and stick models We are going to do a laboratory where you are going to get to make ball and stick models of organic molecules Out of toothpicks and marshmallows! Read over the laboratory assignment for homework.

9. 3-D model Shows how the atoms are arranged in a molecule Is able to be moved or turned, allowing you to view the molecule from different angles 3D model