Check for Understanding Complete the following on a whiteboard. Be prepared to share our your answer and process! (be sure to include significant figures and units!) • Diamonds are measured in carats, and 1 carat = 0.200g. The density of diamond is 3.51g/cm3. What is the volume of a 5.0 carat diamond?
Learning Objectives • I can use evidence to explain why atomic models have changed through history. • I can calculate the molar mass of a compound. • I can name compounds and write formulas for binary compounds, ternary compounds (those with polyatomic ions), and acids. • **Memorize the chemical formulas and charges of the polyatomic ions and the most common transition metal ions. • See list on blog!
Chapter 2: Atoms, Molecules, and Ions • Ted Ed Video – Atomic Theory • Crash Course Video – Atomic Theory • **Please note the following notes are just highlights. Please read text for more detail.**
History of the Atom • Atomic models have been around since Democritus first thought about dividing matter into smaller and smaller pieces until it could no longer be cut: atomos. The idea of the atom was opposed by Aristotle and took around 2500 years until scientific evidence was used to revive the idea of atoms.
History of Atom Cont… • John Dalton • Based on the work of many scientists. • Dalton’s 4-part model • 1. Each element is made of atoms. • 2. Atoms of a given element are identical; atoms of different atoms are different in some fundamental ways. • 3. Atoms can combine to form compounds and a given compound always has the same relative number and types of atoms. • 4. Chemical reactions involve rearrangement of the ways the atoms are bonded together. The atoms themselves are not changed.
History of the Atom Cont… Fundamental Chemical Laws • The Law of Conservation of Mass • Mass is neither created nor destroyed, it is conserved. • The Law of Definite Proportions • The law of definite proportions states that a given compound always contains exactly the same proportions of elements by mass. (water) • The Law of Multiple Proportions • The law of multiple proportions: When two elements form a series of compounds, the ratio of masses of the second element that combine with 1 gram of the first element can always be reduced to the smallest whole numbers.
The Atomic Structure • The electron- • J.J. Thomson 1898-1903 – cathode ray tube • Plum pudding model (positive charge with negative electrons-plums) • Robert Millikan -1909 • Oil drop experiment determined the mass of the electron • 1911 Ernest Rutherford bombarded a thin sheet of metal foil with alpha particles • Nuclear atom idea rejected the plum pudding.
Isotopes • Atoms with the same number of protons but different numbers of neutrons. • Isotopes show almost identical chemical properties because the number of electrons remains the same and the chemistry of an atom is due to its electrons. • * Most elements are a mixture of isotopes*
Atomic (Z) & Mass (A) Number • Atomic Number (Z) • Number of protons written as a subscript in front of chemical symbol • Mass Number ( A) • Total number of protons and neutrons written as a superscript in front of the chemical symbol
Practice • Unit 1 – home learning #9 (Isotope tables) • Model • 5 Minutes
Molecules • Chemical bonds • Forces that hold atoms together in compounds (i.e. sharing electrons) • Covalent bonds share electrons to form molecules. • Chemical formula is used to represent a molecule. • Chemical symbol used to identify element and subscripts indicate the relative number of atoms. (water, octane, oxygen)
Ions • Ionic bonds electrons are transferred. • Chemical bond results from the attractions among ions. • Ion is an atom or group of atoms that has a net positive (cation) or net negative charge (anion). (table salt) • Ionic solid- salt – contains oppositely charged ions.
Periodic Table Intro • Most elements are metal • Metals have characteristic physical properties • Good conductors of heat and electricity • Malleability • Ductility • Lustrous appearance (often) • Metals tend to lose electrons (cations) • Nonmetals • Upper right of PT (except Hydrogen) • Gain electrons (anion) • Typically bond via covalent bonds • Why does this make sense? • Dr. HOFINBrCl (Diatomics)
Periodic Table Intro Cont… • Arrangement • Vertical columns = Groups or Families (similar chemical properties….such as?) • Alkali Metals • Alkaline Earth Metals • Halogens • Noble Gases • Horizontal rows = Periods • We will cover the Periodic Table in much more detail later!
Practice • Review Packet • Ionic Compounds • Compounds with Hydrogen • Covalent Compounds
Lab Materials • Grab a Green Lab Book (DO NOT WRITE IN/ON!) • Grab a Black Lab Binder (DO NOT WRITE IN/ON!) • The rest of today is for you to continue working on Chapter 1 & 2! • ASK QUESTIONS…Work together!
For Tomorrow… • Complete Part 1 of Unit 1 Packet • Read Lab A: Empirical Formula (Black Binder) and complete pre-lab, FOR !! • Read Chapter 3 - Stoichiometry pages 77-113.
Lab Safety • Lab Safety Video • Lab Safety Contract • Lab Expectations