Part I: Structure of Matter
What is Matter? Matter is anything with mass and volume (occupies space). Matter is composed of atoms. Note: Atoms are different from cells. Cells are the basic unit of all living things. Atoms are the basic building blocks of matter.
Inside an Atom There are two regions in the atom, the nucleus and the electron cloud. Atoms are composed of subatomic particles: Protons: positive charge, located inside the nucleus Neutrons: no charge, located inside the nucleus Electrons: negative charge, orbit around the nucleus in the electron cloud
History of an Atom
Comparing Subatomic Particle Sizes The masses of atoms and their subatomic particles are measured in atomic mass units, or amu. A proton and a neutron each have a mass of one amu. An electron is much smaller, with a mass of 1/2,000 amu. Because the mass of electrons is so small, their mass does not really affect the total mass of an atom.
PHET Simulation: Build an Atom Go to https://phet.colorado.edu Click on Play with Simulations Click on Chemistry Click on Build an Atom Spend 5 minutes exploring either Atom or Symbol, then click on the Game.
Part II: Introduction to the Periodic Table
I am Dmitri Mendeleev! I began the periodic table by attempting to classify elements based on their chemical properties. I noticed patterns that led me to the creation of the periodic table.
What is the PERIODIC TABLE? Shows all known elements in the universe Organizes the elements by chemical properties
How do you read the PERIODIC TABLE?
What is the ATOMIC NUMBER? The number of protons found in the nucleus of an atom In an uncharged atom this is also the number of electrons surrounding the nucleus of the atom
What is the SYMBOL? An abbreviation of the element name Often comes from the element s Latin or Greek name The first letter is always capitalized & the second letter is always lowercase
What is the ATOMIC WEIGHT? The number of protons and neutrons in the nucleus of an atom Expressed as relative atomic mass because elements have different isotopes
How do I find the number of protons, electrons, and neutrons in an element using the periodic table? # of PROTONS = ATOMIC NUMBER # of ELECTRONS = ATOMIC NUMBER (in an uncharged atom) # of NEUTRONS = ATOMIC WEIGHT - ATOMIC NUMBER
Just for fun a song!
Electron Organization Electrons organize themselves by shells around the element s nucleus (middle) The outermost shell s electrons are called valence electrons Nucleus Valence Electrons
What else do I need to know to read the periodic table? The periodic table is laid out in horizontal rows and vertical columns Vertical columns are called groups or families Horizontal rows are called periods
Periodic Table Periods In each period, the atomic numbers increase from left to right The periods are numbered 1 through 7 on the left-hand side of the table
Periodic Table Families Members of the families in the periodic table have similar properties The families are labeled at the top of the columns using the numbers 1-18
Alkali Metals Very reactive metals Do not occur freely in nature In reactions, these elements all tend to lose a single electron due to having one valence electron in their outer shell (oxidation number +1) Softer than most other metals Consist of lithium, sodium, potassium, rubidium, cesium, and francium
Alkaline Earth Metals Very reactive metals Do not occur freely in nature In reactions, these elements tend to lose two electrons due to having two valence electrons in their outer shell (oxidation number +2) Consist of beryllium, magnesium, calcium, strontium, barium, and radium
Oxygen Group They all tend to gain two electrons in reactions due to having 6 valence electrons in their outer shell (oxidation number -2) Consist of oxygen, sulfur, selenium, tellurium, and polonium
Halogens They all tend to gain a single electron in reactions due to having 7 valence electrons in their outer shell (oxidation number -1) Halogen means salt-former thus compounds containing halogen elements are called salts Non-metals Consist of fluorine, chlorine, bromine, iodine, and astatine
Noble Gases Very un-reactive due to a maximum number of valence of electrons in their outer shell (oxidation number 0) For a long time, they were called the inert gases, because people thought that these elements wouldn t react at all Non-metals Consist of helium, neon, argon, krypton, xenon, and radon
Other Important Element Classes Metals: About 80% of the elements are metals Common physical properties: Good conductors of heat and electric current High luster (shiny), ductile, and malleable Mostly solid at room temperature Common chemical properties: Metals can bond with non-metals to make salts
Other Important Element Classes Non-Metals: Great variation in physical properties Most are gases at room temperature Poor conductors of heat and electric current (carbon is an exception) Brittle
Other Important Element Classes Metalloids: Properties similar to metals and nonmetals depending on the condition in which they are used