Chapter 2 Flashcards
(31 cards)
Allotropic modifications (allotropes)
Different forms of the same element in the same physical state
Anhydrous
without water
Anion
an ion with a negative charge
atom
the smallest particle of an element that maintains its chemical identity through all chemical and physical changes
atomic mass unit (amu)
one twelfth of the mass of an atom of the carbon-12 isotope; a unit used for stating atomic and formula weights
atomic number
the number of protons in the nucleus of an atom
atomic weight
Weighted average of the masses of the constituent isotopes of an element; the relative mass of atoms of different elements
avogadro’s number
6.022 x 1023 units of a specified item
cation
an ion with a positive charge
chemical formula
combination of element symbols that indicates the chemical composition of a substance
composition stoichiometry
describes the quantitative (mass) relationships among elements in compounds
formula
combination of element symbols that indicates the chemical composition of a substance
formula unit
the smaller repeating unit of a substance – for non-iconic substances, the molecule
formula weight
the mass, in atomic mass units, of one formula unit of a substance. Numerically equal to the mass, in grams, of one mole of the substance. This number is obtained by adding the atomic weights of the atoms specified in the formula
hydrate
A crystalline sample that contains water, H2O, and another compound in a fixed mole ratio. Examples include CuSO4*5H2O and (COOH)2*2H2O
ion
an atom or group of atoms that carries an electric charge. A positive ions is a cation; a negative ion is an anion.
ionic compound
A compound that is composed of cations and anions. An example is sodium chloride, NaCl.
law of constant composition/law of definite proportions
Different samples of a pure compound always contain the same elements in the same proportions by mass; this corresponds to atoms of these elements in fixated numerical ratios.
What is also known as the law of constant composition?
What is also known as the law of definite proportions?
Law of multiple proportions
When two elements, A and B, form more than one compound, the ratio of the masses of element B that combine with a given mass of element A in each of the compounds can be expressed by small whole numbers
molar mass
the mass, in grams, of one mole of a substance; numerically equal to the formula weight of the substance
mole
6.022 x 1023 (Avogadro’s number of) formula units (or molecules, for a molecular substance) of a substance. The mass, in grams, of one mole is numerically equal to the formula (molecular) weight of the substance
molecular formula
a formula that indicates the actual number of atoms present in a molecule of a molecular substance
molecular weight
The mass, in autonomic mass units, of one molecule of a non-iconic (molecular) substance. Numerically equal to the mass, in grams, of one mole of such a substance. The number is obtained by adding the atomic weights of the atoms specified in the formula.
