Lesson 6: Periodic Table & Atomic Theory

Transcription

1 Lesson 6: Periodic Table & Atomic Theory

2 Do Now 7Hg In CJ, copy info down from board. Keep CJs out and open on your desk. On Do Now page, copy and answer questions below. 1. Name 4 properties of metals. 2. Name 4 properties of nonmetals. 3. When Mg ionizes, it will have protons and electrons.

3 Lesson 6: Periodic Table & Atomic Theory

4 Definitions Element: fundamental substance that cannot be broken down by ordinary chemical means into simpler substances; all matter consists of ~100 elements Atom: smallest particle of an element that can exist; smallest unit of an element that can enter into a chemical reaction

5 Atoms are comprised of 3 SUBATOMIC PARTICLES: 1 amu nucleus +1 1 amu nucleus electron cloud chemical bonding -1 0 amu 0

6 Electron cloud Nucleus: protons and neutrons

7 Counting Subatomic Particles

8 Electrons When atoms gain or lose electrons, the goal is to become stable and have a full outer electron shell. neutral ions Becomes a cation, more protons than electrons Becomes an anion, more electrons than protons outer most

9 Electron cloud Nucleus: protons and neutrons Valence shell Electron shells

10 columns

11 anion with charge of 2- cation with charge of 2+ cation with charge of 3+ anion with charge of 1- gain 2 lose 2 lose 3 gain 1 metals and nonmetals left gain lose or gain right lose between

12 Neutrons Mass number of this isotope 35 Cl Atoms of the same element that have different numbers of neutrons are called. isotopes For example, 75.78% of naturally occurring Chlorine exists as 35 Cl while 24.22% exists as 37 Cl Cl has protons and neutrons while 37 Cl has protons and neutrons. The relative abundance of these isotopes is considered in the average atomic mass of Chlorine on the Periodic Table.

13 Atomic Mass The atomic mass of an atom is the atom's weight standardized to a carbon-12 atom Gives the atom's weight in Atomic Mass Units or AMUs Relative atomic mass of an element = average of the weight of all isotopes in a normal environment on the Earth's crust Average atomic mass of an element = average mass of a given sample

14 Relative atomic mass amu

15 Pop question: Do protons and neutrons participate in chemical reactions? Nope.

16 Mass number & atomic mass in amu 35 Cl Cl Element symbol Mass number & atomic mass in amu Atomic number 17 Cl Atomic number Molar mass in grams & relative atomic mass in amu Chlorine-35 Cl - Charge of ion Mass number & atomic mass in amu

17 Definitions Atomic number: number of protons Mass number: number of protons + neutrons Atomic mass: mass of atom in amu or Da

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19 Do Now 7Pb, B, Zr Pb & B: Take HW 7.8 out to be checked. In CJ, copy info down from board. Keep CJs out and open on your desk. Take out the packet given to you last week (sub packet) On Do Now page #4, copy and answer questions below. 1. When ionized, Cl loses/gains electrons to form charge. 2. Helium has electron shells. 3. What is the technique of chromatography used for?

20 HW & Study Guide Review

21 from the Periodic Table equals the Atomic number Subtract the mass number from the atomic number Aluminum = = Sodium = Iodine 53 I =

22 Periodic Table Organization ion formed number of valence electrons electron shells

23 Alkali metals Alkaline earth metals Halogens Noble gases Transition metals none varies

24 metals metalloids nonmetals

25 Metals, Nonmetals, Metalloids: Properties Metals: solids at room temperature (Hg is an exception), high luster, good conductors of electricity and heat, malleable, ductile, most have a high melting point and high density, easily lose electrons, low electronegativity Many metals are reactive readily chemically combine with nonmetals to form compounds. Less reactive metals can be found in a native, free state (copper, gold, silver). Metals can be mixed to form alloys (brass, bronze, steel). Nonmetals: not lustrous, relatively low melting points and densities, poor conductors of heat and electricity, high ionization energies, high electronegativities, brittle solids (not malleable or ductile), easily share or gain valence electrons, dull (not metallic) Nonmetals exist in different states solids (carbon, sulfur, iodine, phosphorous, selenium), liquid (bromine) and gases (rest of nonmetals). Nonmetals combine with other nonmetals to form molecular compounds (carbon dioxide CO 2, methane CH 4, sulfur dioxide SO 2 ). Fluorine is the most reactive nonmetal. Metalloids: properties that are intermediate between those of metals and nonmetals; semiconductors.

26 Elements that Exist as Diatomic Molecules Hydrogen H 2 Oxygen O 2 Nitrogen N 2 Fluorine* F 2 Chlorine* Cl 2 Bromine* Br 2 Iodine* I 2 colorless gas colorless gas colorless gas pale yellow gas yellow-green gas reddish brown liquid bluish-black solid

27 Discovery of the Electron J. J. Thompson Discovered by. cathode tube Used a to study electric current. The glowing beam he observed was actually electrons. Seeing a paddle wheel rotate inside the cathode mass tube showed that electrons have.

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29 Ernest Rutherford and the gold foil experiment NOT ON TEST #1 The gold foil experiment revealed that the atom is comprised mostly of empty space with a dense, small positively-charged nucleus.

30 NOT ON TEST #1 Some alpha particles were deflected (by the nuclei of the gold atoms) while many particles went straight through the atom. If a dense positively charged nucleus did not exist, all alpha particles would have travelled straight. Model proposed a small dense nucleus of the atoms were causing the alpha particles to deflect.