Chemistry Ch 2
Isotope
different weight of atom due to different number of neutrons (chemically identical still)
Metalloids
elements that have physical/chemical properties of metals and nonmetals; semiconductors
Cation
gaining of electrons (metals)
Rutherford
gold foil; emissions; dense particle in middle (nucleus)
Lavoisier
law of conservation of mass
Proust
law of definite proportions
Dalton
law of multiple proportions; atomic theory
Anion
loss of electrons (nonmetals)
Chadwick
neutron (mass discrepancy)
Mass #
p + n ; A
Natural Abundance
percentage of an element in the state of a certain isotope
Mendeleev
periodic table
Curie
radioactivity
Period
rows of periodic table
Bennig & Rohrer
scanning tunneling microscope
Atomic #
# of protons; Z
Metals
1. tend to form cations 2. solid at room temperature 3. reflective surface 4. good heat and electricity conductors 5. malleable and ductile lower left side of table
Hydrogen and oxygen form both water and hydrogen peroxide. The decomposition of a sample of water forms 0.125 g hydrogen to every 1.00 g oxygen. The decomposition of a sample of hydrogen peroxide forms 0.25 g hydrogen to every 1.00 g oxygen. Show that these results are consistent with the law of multiple proportions.
0.25 g 2 0.125 g
Noble Gases
1. gas at room temperature 2. low melting/boiling points 3. nonreactive/inert
Alkaline Earth Metals
1. hard 2. high melting/boiling points 3. high density 4. flame test 5. reactive 6. form stable, insoluble oxides 7. basic
Atomic Theory
1. indestructible particles 2. all atoms of given element have same mass and properties 3. atoms combine in simple, whole ratios 4. atoms of one element cannot change into atoms of another element in a chemical reaction (only one that still stands)
Alkali Metals
1. low density 2. soft 3. low melting/boiling points 4. flame test 5. reactive 6. never found uncombined in nature 7. tend to form water soluble compounds
Halogens
1. nonmetals 2. diatomic 3. reactive 4. reacts with metal to form ionic compounds 5. acidic
Nonmetals
1. tend to form anions 2. -ide 3. found in all three states 4. poor conductors of heat and electricity 5. solids are brittle 6. upper right side of the periodic table
Nitrogen form several compounds with oxygen, including nitrogen dioxide and dinitrogen monoxide. Nitrogen dioxide contains 2.28 g oxygen to every 1.00 g of nitrogen, while dinitrogen monoxide contains 0.570 g oxygen to every 1.00 g nitrogen. Show that these results are consistent with the law of multiple proportions.
2.28 g oxygen 4.00 0.570 g oxygen
Mass Ratio: 14.0 g N / 3.0 g H
4.7 or 4.7:1
Mass Ratio: 16.0 g O/ 2.0 g H
8.0 or 8:1
Law of Definite Proportions
All samples of a given compound, regardless of their source or how they were prepared, have the same proportions of their constituent elements.
Law of Conservation of Mass
In a chemical reaction, matter is neither created nor destroyed.
Two samples of carbon monoxide are decomposed into their constituent elements. One sample produces 17.2 g of oxygen and 12.9 g of carbon, and the other sample produces 10.5 g of oxygen and 7.88 g of carbon. Show that these results are consistent with the law of definite proportions.
Mass Oxygen = 17.2 1.33 or 1.33:1 Mass Carbon = 12.9 Mass Oxygen = 10.5 1.33 or 1.33:1 Mass Carbon = 7.88
Two samples of carbon dioxide are decomposed into their constituent elements. One sample produces 25.6 g of oxygen and 9.60 g of carbon, and the other produces 21.6 g of oxygen and 8.10 g of carbon. Show that these results are consistent with the law of definite proportions.
Mass Oxygen = 25.6 2.67 or 2.67:1 Mass Carbon = 9.60 Mass Oxygen = 21.6 2.67 or 2.67:1 Mass Carbon = 8.10
Law of Multiple Proportions
When two elements (A and B) for two different compound, the mass of element B that combine with 1 g of element A can be expressed as a ratio of small whole numbers.
JJThomson
cathode ray; electrons
Ion
charged atom through gaining/losing electrons
Group/Family
columns of periodic table
