Chapter 2 Flashcards
Johann Wilhelm
Discovered that when voltage is applied in a glass tube containing a gas at a low pressure, the cathode emits a beam of cathode rays towards the anode. The glass behind the cathode glowed
What are cathode and anodes?
Cathode: Negative electrode
Anode: Positive electrode
JJ. Thompson
Discovered electrons(particles in cathode rays) and that cathode rays are deflected by magnetic and electric fields. Cathode rays always behave the same way and have the same mass to charge ratio. The beam from cathode ray tube is deflected toward positively charged plate, away from the negatively charged plate. Made the plum pudding model of the atom where electrons are distributed throughout a diffuse, positively charged amotsphere.
Robert Millikan
Advanced Thompson’s work and determined the mass and charge of an electron with his oil drop experiment. Mass=9.109E-28g. Charge=-1.602E-19 C
Henri Becquerel
Discovered that some materials produce invisible radiation consisting of charged particles by studying pitchblende
What is radioactivity/radiation and what are the types?
Spontaneous emission of high energy radiation and particles. Beta particles are high energy electrons that penetrate solids better and alpha particles have a +2 charge and their mass=He nucleus
Rutherford’s gold foil experiment
Rutherford bombarded a thin gold foil with alpha particles to test Thompson’s model of the atom, he did not get expected results. He expected most alpha particles to go through and some get slightly deflected, while most passed through, some were deflected by 90 degrees and same were deflected backwards. This revealed a positively charged nucleus that is much larger than an alpha particle in the middle of the atomic
James Chadwick
A student of Rutherford. He bombarded a thin beryllium sheet with alpha particles and a very high energy radiation was emitted by the metal that was not deflected by either electric or magnetic fields. the radiation came from these newly discovered neutrons
Unit used to measure atomic distances
picometer(pm) or angstrom(A)
Why do we use the unified atomic mass unit instead of the atomic mass unit?
The amu=6protons+6electrons. This was meant to represent the mass of a carbon 12 nucleus but they are not actually equal. Mass of the carbon 12 nucleus+6electrons(1 whole atom)=12u exactly
Aston’s experiment
Discovered the existence of isotopes by discovering the 2 different types of neon gas exist. He fired cathode rays at different neon isotopes and discovered different deflection angles
Nuclide
an atom(or nucleus) with a specific number of protons and neutrons
Average atomic mass
Weighted average of masses of all STABLE isotopes of an element
Dmitri Mendeleev
Ordered elements by atomic mass, arranged elements based on similar chemical and physical properties and left open spaces for elements not discovered. He gave a solid foundation for the periodic table we have now
Periods
Horizontal rows in the periodic table
Families/Groups
Vertical columns in the periodic table that tend to have the same physical and chemical properties
Properties of Metals
Shiny solids, conduct heat and electricity, malleable, ductile
Properties of Nonmetals
Solids, liquids and gases. Nonconductors, solids nonmetals are brittle
Properties of metalloids
Between metals and nonmetals, shiny solids, brittle, semiconductors
Alkali Metals
Group one of the periodic table(excluding hydrogen)
Alkaline earth metals
Group 2 of the periodic table
Halogens
Group 17 of the periodic table
Noble/rare gases
Group 18 of the periodic table
Law of multiple proportions
The ratio of the two masses of one element that react with a given mass of another element to form two different compounds is the ratio of two small numbers
Molecular compounds
Composed of atoms held together in molecules by covalent bonds, composed on nonmetals
Covalent bonds
Bond between 2 atoms created by sharing one or more pairs of electrons
Ionic compound
Consist of ions formed by transfer of electrons between atoms, held together by electrostatic forces, and are composed of a metal and a nonmetal. Metals form cations and nonmetals form anions
Charges of groups 1, 2, and 17
1: +1
2: +2
3: -1
Formula unit
Smallest electrically neutral unit of an ionic compound
What is special about Mercury and Gallium being classified as metals?
Mercury is liquid at room temperature, Gallium is solid but has a very low melting point as well
What is special about At being classified as a metalloid?
It is too unstable to be worked with so it is predicted to be a metalloid
Oxoanions
Polyatomic ions containing oxygen in combination with one or more other elements
Binary Acids
Contain hydrogen and a monoatomic anion(mostly halogens)
Neutron capture
When individual neutrons collide and fuse with atomic nuclei
Denotation of hydrogen 2 isotope and it’s name
2D or D, deuterium
Name and denotation of hydrogen 3 isotope
3T or T, Tritium
Energy of fusion
solid to liquid
