Ch 2: Atoms, Ions, and Molecules Flashcards
What is Dalton’s Atomic Theory?
everything is composed of atoms, atoms of the same element are all identical, atoms of different elements are different, compounds are composed of atoms of two or more different elements, atoms in compounds combine in whole number ratios
What does the law of definite proportions state?
different samples of the same compound always contain that compound’s constituent elements in the same proportion by mass
What does the law of multiple proportions state?
when more that one compound contains the same elements the ratio of the ratio of the elements is a small whole number
What does the law of conservation of mass state?
matter can be neither created nor destroyed
What is radiation?
the emission and transmission of energy through space in the form of waves
J.J. Thomson
he used a cathode ray tube and his knowledge of electromagnetic theory to determine the ratio of electric charge to the mass of an individual electron
R. A. Millikan
he succeeded in measuring the charge of the electron (-1.6022 x 10^-19 C) and the mass (9.10 x 10^-28 g) by examining the motion of single tiny drops of oil that picked up static charge from ions in the air.
What is radioactivity?
the spontaneous emission of particles and/or radiation
What are Alpha (a) rays?
positively charged particles, called a particles, and therefore are deflected by the positively charged plate
What are Beta (weird B) rays?
they’re electrons and are deflected by the negatively charged plate
What are Gamma (Y) rays?
y rays have no charge and are not affected by an external field
E. Rutherford
he gave us the modern picture of an atom by using very thin foils of gold and other metals as targets for a particles from a radioactive source
What is an atomic number (Z)?
the number of protons in the nucleus of each atom of an element
What is a mass number (A)?
the total number of neutrons and protons present in the nucleus of an atom of an element
What are isotopes?
atoms that have the same atomic number (Z) by different mass numbers (A)
How are isotopes identified?
with their element and mass numbers
What are periods on the periodic table?
horizontal rows
What are groups or families on the periodic table?
vertical columns
Group 1 elements are called:
alkali metals
Group 2 elements are called:
alkaline earth metals
Group 17 elements are called:
halogens
Group 18 elements are called:
noble gases
What is a molecule?
an aggregate of at least two atoms in a definite arrangement held together by chemical forces (chemical bonds)
What are diatomic molecules?
molecules containing only two atoms
What are polyatomic molecules?
molecules containing more than two atoms
What is an ion?
a charged atom
What is a cation?
an ion with a net positive charge
What is an anion?
an ion whose net charge is negative
What is a monatomic ion?
an ion containing only one atom
What is a polyatomic ion?
an ion containing more than one atom
What does a chemical formula express?
the composition of molecules and ionic compounds in terms of chemical symbols
What are considered inorganic compounds?
ionic compounds, molecular compounds, acids and bases, and hydrates
What is an acid?
a substance that yields hydrogen ions (H+) when dissolved in water
What are oxoacids?
acids that contain hydrogen, oxygen, and another element (the central element)
