Crash Course on Nucleus

Transcription

1 II. Chemistry

2 Crash Course on Nucleus

3 A. Atomic Theory 1. Atom a. Most basic unit of matter - building block b. Can t be broken down further and still retain its properties c. Identified by the number of protons in its nucleus d. Recognized by its atomic number and a one or two letter abbreviation 2. Element a. A pure chemical substance consisting of a single type of atom. b. Example: Hydrogen, Oxygen, Gold

4 3. Parts of an Atom a. Proton (p+) 1) Positively charged particles 2) Mass much greater than electrons 3) Number of Protons = Atomic Number 4) Inside the Nucleus 5) Bound to Neutron by the Strong Force b. Neutron (n) 1) Neutrally charged particles (no charge) 2) About the same mass as a Proton 3) Equal to or more than the number of Protons 4) Inside the Nucleus

5 c. Electron (e - ) 1) Negatively charged particles 2) Balance the charge of Protons a) usually the same number protons=electrons 3) Create a cloud of negative energy around the atom 4) Move in rapid and random motion around the nucleus 5) Held to the nucleus by the electromagnetic force d. Nucleus 1) Contains Protons and Neutrons 2) Held together by the strong force

6 e. Ion 1) An electrically charged atom formed by the loss or gain of one or more electrons 2) The valence of an ion is equal to the number of electrons lost or gained and is indicated by plus or minus signs Example: Na + Cl - f. Isotope 1) Atoms of the same element that have a different set number of neutrons (isotope of an element) 2) Each have different atomic masses 3) Number of protons stay the same (identity number)

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8 B. Periodic Table 1. Display of all known elements arranged by Atomic Number 2. Developed by Dmitri Mendeleev (1869) a. left gaps - predicted missing elements 3. Organization a. Elements arranged into 7 periods and 18 groups b. Period - (horizontal row) atomic number increases by 1* c. Group - (vertical column) usually elements in the same group have the same number of valence electrons and similar chemical properties and characteristics d.* Elements fits into period 6 *Elements fit into period 7

9 Interactive Periodic Table

10 B. Periodic Table 1. Display of all known elements arranged by Atomic Number 2. Developed by Dmitri Mendeleev (1869) a. left gaps - predicted missing elements 3. Organization a. Elements arranged into 7 periods and 18 groups b. Period - (horizontal row) atomic number increases by 1* c. Group - (vertical column) usually elements in the same group have the same number of valence electrons and similar chemical properties and characteristics d.* Elements fits into period 6 *Elements fit into period 7

11 The Genius of Mendeleev

12 4. Classifications within the Periodic Table a. Alkali Metals - 1 valence electron, very reactive, soft, low density, in nature occur as positive ion b. Alkaline Earth Metals - 2 valence electrons, somewhat reactive, in nature occur as positive ions c. Transition Metals - safe to touch, malleable, ductile, excellent conductors, various valence electrons, high melting point and boiling point, (Hg the only liquid) most widely used elements d. Basic Metals - varied valence electrons, ductile, malleable, not good conductors, high densities, all are solids at room temp.

13 e. Semimetals (semi-conductors) properties of both metals and nonmetals, are useful in computers, calculators and phones f. Nonmetals - C, H, N, O, P, S, Se, poor conductors, brittle, do not reflect light, make up living things, H, N, O gas at room temp g. Halogens - 7 valence electrons, gains one electron to become stable, poisonous nonmetals, very reactive (especially with Alkali Metals) h. Noble Gases - Have filled valence shells, all are colorless, odorless gases, all glow a unique color when electrified i. Lanthanides - Rare Earth Metals, soft, reactive, burn in oxygen, spark when struck, not very conductive, j. Actinides - all radioactive, most are man-made by adding protons to U, U is the most stable element in the group

14 C. Classification 1. Matter is classified in three ways: a. Elements 1) Atoms 2) Molecules - like atoms bonded together

15 How Small are Atoms - Ted

16 b. Compounds 1) pure substances made up of two or more elements combined in fixed proportions 2) Each has a chemical formula that indicates the ratio of the elements present 3) Examples: NaCl - Table Salt (1 sodium atom with 1 chloride atom) H 2 O - Water (2 hydrogen atoms with 1 oxygen atom) NH 4 - Ammonia (1 nitrogen atom for every 4 hydrogen atoms) Mg 3 (PO 4 ) 2 Magnesium Phosphate ( 3 magnesium atoms, 2 phosphorus atoms, 8 oxygen atoms)

17 Ted Ed Mixtures I

18 c. Mixtures 1) Any substance that cannot be classified as an element or a compound 2) Not combined through chemical reaction 3) Heterogeneous (different) (salad, trail mix, OJ w/pulp) -not uniform properties throughout 4) Homogeneous (same) (salt water, vanilla ice cream) - the same throughout the mixture - solution

19 5) Solution (Homogeneous mixture) a) Solute - the substance that dissolves (to mix uniformly at a molecular level) b) Solvent - The substance that causes the solute to dissolve c) Example: salt water - salt is solute, water is solvent

20 Ted Ed Mixtures II

21 D. Change in Matter 1. Physical Change (review) a. Affects physical properties of a substance (size, shape, state of matter) b. Does not change the identity of substance c. Examples: ice water; cutting paper in half; squishing a ball of clay 2. Chemical Change a. Changes a substance into a new substance (new identity?) b. Properties are different from the original c. Usually changes cannot be reversed (un-burn?) d. Examples: metal rusting; cooking an egg; vinegar reacting with baking soda

22 3. Chemical Reactions - evidence when a chemical change occurs a. Formation of gas (seen as bubbles) b. A change in color or odor c. The formation of a precipitate (a solid formed when 2 clear liquids are mixed) d. The absorption or release of heat or light e. A permanent change in the identity of the substance

23 4. Energy and Chemical Reactions a. Energy is stored in bonds between atoms b. When bonds break - energy is released c. When bonds form - energy is stored d. Exothermic Reactions - (exo = out, thermic = heat) releases heat; gets hotter e. Endothermic Reactions - (endo = go in, thermic = heat) stores heat; gets cooler

24 5. ph a. A method of expressing the hydrogen ion concentration (acidity) of a solution (power of Hydrogen ions) b. Mathematical formula ph = -log [H + ] TMI? c. Hydrogen ion (Hydronium H 3 O) - high concentration in acids - low concentration in bases d. Acid - ph value from e. Base (Alkali) - ph value from f. Neutral g. A change in acidity of one full ph equals a 10 x change in the concentration of hydrogen ions

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