Atoms and the periodic table Pre-chem ch. 3 Atoms and the periodic table

Pre-chem ch. 3 Lo Describe the emergence of the Periodic Table Determine an elements: protons, neutrons, electrons, family, period, atomic mass, atomic number. Describe patterns on the Periodic Table, including relationship between electrons and group characteristics Determine a Determine an elements electron energy level Convert between moles and mass

Atoms Every element is made of tiny, unique particles called atoms that cannot be subdivided Atoms of the same element are exactly alike Atoms of different elements can join to form molecules

Variations on the atom Aristotle Democritus Dalton Bohr

Electrons Energy levels- e- can only be in certain E levels, they must gain E to move to a higher level or lose E to move to a lower E level Valence electrons

What an atom consists of

Periodic table key

Determining the make up of an element Protons (p+) Electrons (e-) Neutrons (n) Atomic mass Atomic number C 6 (12.01) 12 Mg O Zn Fe

Atom vs. ion Atom Ion P+ and e – are equal Atomic number = #p+ No charge Neutrons plus protons= atomic mass P+ and e – are NOT equal Atomic number = #p+ Charge Cation Anion Neutrons plus protons= atomic mass

How to figure out electrons in an ion Charge= protons- electrons -2= 10 protons – X electrons X = 12 electrons +3 = 10 protons – X electrons X= 7 electrons

Atom or ion practice Element Atom/ion A Mass A# p+ e- n O2- Ion 16 8 10 Mg+2 Na+ Na Fe+3

isotope Hydrogen Isotopes Protium Deutrium Tritium Carbon 12, 13, 14 Nitrogen 12, 14

Perioidc table lay out

QR code to Periodic table.. No way! Open and scan each element to hear a short video on it, courtesy of University of Nottingham QR code periodic table

Families of elements

Potassium, K reacts with water and must be stored in kerosene Alkali Metals (group 1) All alkali metals have 1 valence electron Alkali metals are NEVER found pure in nature; they are too reactive Reactivity of these elements increases down the group Group info from sciencegeek.net Potassium, K reacts with water and must be stored in kerosene

Alkaline Earth Metals (group 2) All alkaline earth metals have 2 valence electrons Alkaline earth metals are less reactive than alkali metals Alkaline earth metals are not found pure in nature; they are too reactive The word “alkaline” means “basic” common bases include salts of the metals Ca(OH)2 Mg(OH)2

Properties of Metals Metals are good conductors of heat and electricity Metals are malleable Metals are ductile Metals have luster

Transition Metals Copper, Cu, is a relatively soft metal, and a very good electrical conductor. Mercury, Hg, is the only metal that exists as a liquid at room temperature

Properties of Metalloids They have properties of both metals and nonmetals. Metalloids are more brittle than metals, less brittle than most nonmetallic solids Metalloids are semiconductors of electricity Some metalloids possess metallic luster

Silicon, Si – A Metalloid Silicon has metallic luster Silicon is brittle like a nonmetal Silicon is a semiconductor of electricity Other metalloids include: Boron, B Germanium, Ge Arsenic, As Antimony, Sb Tellurium, Te

Nonmetals Nonmetals are poor conductors of heat and electricity Nonmetals tend to be brittle Many nonmetals are gases at room temperature Carbon, the graphite in “pencil lead” is a great example of a nonmetallic element.

Examples of Nonmetals Microspheres of phosphorus, P, a reactive nonmetal Sulfur, S, was once known as “brimstone” Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure

Halogens Halogens all have 7 valence electrons Halogens are never found pure in nature; they are too reactive Halogens in their pure form are diatomic molecules (F2, Cl2, Br2, and I2) Chlorine is a yellow-green poisonous gas

Noble Gases Noble gases have 8 valence electrons (except helium, which has only 2) Noble gases are ONLY found pure in nature – they are chemically unreactive Colorless, odorless and unreactive; they were among the last of the natural elements to be discovered

Electron Energy Levels

orbital

P orbital

D orbital

F orbital

Electron config examples H B O Mg N Fe Zn

Noble gas config (shorthand) Use the noble gas before your element, put it in [brackets] Mg example: [Ne] Subtract that many e- from your total 12-10= 2 Keep going up until you have used all your e- 3s2 Answer Mg= [Ne] 3s2

Noble gas config examples Mg N Fe Zn

Using Moles Avagadro’s number Molar mass= 1 mole 6.022 x 1023 is a mole of a substance (gumballs, H, He, etc) Molar mass= 1 mole

Conversion ex. With molar mass Fe= 5.50 mol Fe mm= 55.85 g/mol Fe Mass of Fe? 5.50 mol Fe 55.85 g Fe 307 g Fe 1 mol Fe

More…. 2.50 mol S is how many g S? 0.50 mol C is how many g C?

352 g Fe is how many mol Fe? 620 g Hg is how many mol Hg? 11g Si is how many mol Si?