Chapter 2 Flashcards
Who proposed the Law of Conservation of Mass and what does it state?
Antoine Lavoisier; total mass in a chemical reaction remains constant.
What is the Law of Definite Proportions?
Different samples of the same compound have elements in fixed mass ratios.
What is the Law of Multiple Proportions?
When two elements form more than one compound, the ratios of masses of one element to a fixed mass of the other are small whole numbers.
Who discovered the electron and how?
J.J. Thomson via cathode ray tube experiment.
What was Millikan’s contribution?
Measured the charge of the electron using the oil drop experiment.
What did Rutherford’s gold foil experiment reveal?
Atoms have a small, dense, positively charged nucleus; most of atom is empty space.
Who discovered the neutron?
James Chadwick, in 1932, through Be bombardment.
What are alpha particles?
Helium nuclei; heavy, positive, low penetration, high ionization.
What are beta particles?
High-speed electrons; lighter, negative, moderate penetration.
What are gamma rays?
High-energy photons; no charge, high penetration, low ionization.
What does the atomic number (Z) represent?
Number of protons (and electrons in a neutral atom)
What is the mass number (A)?
Total number of protons + neutrons.
What are isotopes?
Atoms with the same atomic number but different mass number (i.e., same element, different neutrons).
What is a molecule?
Two or more atoms bonded together, sharing electrons.
What is an ion?
Atom/group with net charge: cation (+), anion (−).
What is an ionic compound?
Formed by cations and anions via electron transfer.
What’s the difference between ionic and covalent bonds?
Ionic = transfer (metal + nonmetal); Covalent = share (nonmetal + nonmetal).
How are ionic compounds named?
Cation name + anion (with “-ide” or polyatomic ion name). Use Roman numerals for transition metals.
How are molecular compounds named?
Prefix + element, second gets “-ide”; omit mono- from first element.
How are acids named?
-ide → hydro- + -ic (e.g., HCl = hydrochloric acid)
-ate → -ic (e.g., HNO₃ = nitric acid)
-ite → -ous (e.g., H₂SO₃ = sulfurous acid)
How are bases named?
Like ionic compounds; name of metal/ammonium + hydroxide.
What are hydrates?
Compounds with water; name: compound + (prefix)hydrate (e.g., CuSO₄*5H₂O = copper(II) sulfate pentahydrate)
What is a covalent bond?
occurs when electrons are shered between two nonmetals
What is an ionic bond?
Occurs when electrons are transferred between a metal and nonmetal
