Chapter 2 Flashcards
Who were the first to try to explain why chemical changes occur and described matter?
Greeks
Who discovered several elements & learned to prepare the mineral acids?
Alchemists
Who created the foundations of modern chemistry in 1400s-1500s?
Georg Baur; Paracelsus
First chemist to perform truly quantitative experiments
Robert Boyle
Who said “phlogiston” flows out of burning material? Who discovered oxygen gas?
Stahl; Joseph Priestley
Who explained nature of combustion & carefully weighed reactants & products?
Antoine Lavoisier
Define law of conservation of mass
Mass is neither created nor destroyed
Lavoisier showed combustion involved __ & life is supported by it
Oxygen
Who found that copper carbonate is always 5.3 parts Cu, 4 parts O, 1 part C by mass?
Joseph Proust
Define law of definite proportion
A given compound always contains exactly the same proportion of elements by mass
Dalton said if elements have ___, compounds always have the __ __ of atoms
Particles; Same combination
Define law of multiple proportions
When 2 elements form a series of compounds, the ratios of the masses of the second element that combine with 1g of the first element can always be reduced to small whole numbers
Describe Dalton’s theory (4)
1) each element is made up of tiny particles called atoms 2) atoms of a given element are identical; the atoms of different elements are different in some way3) chemical compounds are formed when atoms of different elements combine with each other; a given compound always has the same relative numbers & types of atoms4) chemical reactions involve reorganization of the atoms- changes in the way they are bound together; the atoms are not changed in a chemical reaction
Define atomic mass (atomic weights)
The weighted average mass of the atoms in a naturally occurring element
Who developed the modern symbols for elements used in writing formulas?
Berzelius
Describe Avogadro’s hypothesis
At the same temperature & pressure, equal volumes of different gases contain the same number of particles
1860: who found the correct atomic mass of carbon is 12?
Cannizzaro
Describe JJ Thompson’s experiments
Studied electrical discharges in cathode-ray tubes; found when high voltage was applied to the tube, a cathode ray was produced; ray was a stream of electrons
Define cathode rays
Ray emanating from the negative electrode (cathode) in a partially evacuated tube; a stream of electrons
What did Thompson postulate about the atom?
An atom consists of a diffuse cloud of positive charge with negative electrons embedded randomly in it, which created the plum pudding model of the atom
Define electrons
Negatively charged particle that moves around the nucleus of an atom
Define radioactivity
The spontaneous decomposition of a nucleus to form a different nucleus
Three types of radioactive emission
Gamma rays; Beta particles; Alpha particles
Define gamma ray; Define beta particle; Define alpha particle
High-energy “light”; High-speed electron; 2+ charge
Define nucleus
Small, dense center of positive charge in an atom
What did Rutherford discover?
Metal-foil experiment: shot alpha particles at thin foil, some particles deflected (caused by a center of concentrated positive charge containing most of the mass
Define nuclear atom
Atom with a dense center of positive charge with electrons moving around the nucleus at a distance that is large relative to the nuclear radius
Mass of electron; Mass of proton & neutron
9.11 • 10^-31 kg; 1.67 • 10^-27 kg
Define proton
Positively charged particle in an atomic nucleus
Define neutron
Particle in the nucleus with the same mass as a proton with no charge
The nucleus is almost all of an atom’s __; electrons constitute most of the atomic __
Mass; Volume
__ affect interactions with other atoms; atoms of different __ have different chemical behavior; number of __ must equal number of __ to have no net charge
Electrons; Elements; Electrons; Protons
Define isotope
Atom with the same number of protons but different number of neutrons
Define atomic number
Number of protons in the nucleus of an atom
Define mass number
Total number of protons and neutrons in the nucleus of an atom
Isotopes show almost identical __ properties
Chemical
Nucleus size; Atom size; Charge of electron/proton
10^-13 cm; 10^_8 cm; 1.60 • 10^-19 C
Define covalent bond
A type of bond in which electrons are shared by atoms
Define chemical bond
The force, or more accurately, the energy, that holds two atoms together in a compound
Define molecule
A bonded collection of 2 or more atoms of the same or different elements
Define structural formula
The representation of a molecule in which the relative positions of the atoms are shown and the bonds are indicated by lines
Define chemical formula
The representation of a molecule in which the symbols for the elements are used to indicate the types of atoms present and subscripts are used to show the relative numbers of atoms
Define Ball-and-stick model
A molecular model that distorts the sizes of atoms but shows bond relationships clearly
In a compound composed of molecules, the individual molecules move around __
Independently
Define space-filling model
A model of a molecule showing the relative sizes of the atoms and their relative orientations
Define cation
A positive ion; formed by loss of an electron
Define ion
An atom or a group of atoms that has a net positive or negative charge
Define anion
A negative ion; formed by gain of an electron
Define ionic bonding
The electrostatic attraction between oppositely charged ions
Define ionic solid (salt)
A solid containing cations & anions that dissolves in water to give a solution containing the separated ions which are mobile and this free to conduct electricity (simple or polyatomic ions)
Define polyatomic ion
An ion containing a number of atoms
Define metals
An element that gives up electrons relatively easily to form positive ions & is lustrous, malleable, ductile, & a good conductor of heat and electricity
Define periodic table
A chart showing all the elements arranged in columns with similar chemical properties
Define malleable; Define ductility
Can be hammered into thin sheets; Can be pulled into wires
Define nonmetals
An element not exhibiting metallic characteristics; chemically, typical nonmetals accept electrons from a metal to form negative ions
Define transition metals
Metals shown in the center of the periodic table
Nonmetals often bond __ with __ and reacts with __ to form __
Covalently; Nonmetals; Metals; Salts
Define groups (families)
A vertical column of elements having the same valence electron configuration and showing similar chemical properties
Define alkali metals
Group 1A metals; very active elements that readily form ions with a 1+ charge when they react with nonmetals
Define alkaline earth metals
Group 2A metals; all form ions with a 2+ charge with nonmetals
Define halogens
Group 7A elements; all form diatomic molecules and react with metals to form salts containing ions with a 1- charge
Define noble gases
Group 8A elements; all exist under normal conditions as monatomic (single-atom) gases and have little chemical reactivity
Define Periods
Horizontal rows of elements in the periodic table
Define binary compounds
Compounds composed of 2 elements
To name binary ionic compounds: (3)
1) cation is always named first, then the atom2) monatomic cations have the same name as its parent element 3) monatomic anions are named by taking the root of the element name and adding -ide
Define binary ionic compound
Contains a positive ion (cation) and a negative ion (anion)
In formulas of ionic compounds, simple ions are represented by the __ __
Element symbol
The __ on the metal ion must be specified when a metal can form more than one type of positive ion; __ __ indicate the charge of the cation
ChargeRoman numerals
The ion with the higher charge has a name ending in __, and the one with the lower charge has a name ending in __
-ic; -ous
Elements that form only one cation don’t need to be identified by a __ __
Roman numeral
A compound must be __ __; compounds containing __ __ usually having a Roman numeral in its name
Electrically neutral; Transition metals
Although __ & __ are transition metals, they are usually named without a Roman numeral because in virtually all of its compounds, it is found as the __ & __ ions
Silver; Zinc; Ag+; Zn+2
When a metal ion is present that forms more than one type of cation, the charge on the metal ion must be determined by __ the __ & __ charges of the compound
Balancing; Positive; Negative
Define oxyanion
Anions that contain an atom of a given element and different #s of oxygen atoms
When there are 2 members in a series, the one with the smaller # of oxygen atoms ends in __, and the name of the one with the larger # ends in __
-ite; -ate
When more than 2 oxyanions make up a series, __ (less than) and __ (more than) are used as prefixes to name the members of the series with the fewest & the most oxygen atoms
Hypo-; Per-
__ __ __ element names follow the same rules as binary ionic compounds
Binary covalent compounds
Define binary covalent compounds
Compounds formed between two nonmetals
To name binary covalent compounds: (4)
1) the first element in the formula is named first using the full element name2) the second element is named as if it were an anion 3) prefixes are used to denote the number of atoms present 4) the prefix mono- is never used for naming the first element
The final _ or _ of the prefix is usually dropped when the element starts with a vowel
O; A
Define acid
A substance that produces hydrogen ions in solution; a proton donor (can be viewed as a molecule with one or more H+ ions attached to an anion
To name acids (4)
1) if the anion does not contain oxygen, the acid is named with the prefix hydro- and the suffix -ic2) if the anion contains oxygen, the acidic name is formed from the root name of the anion with a suffix of -ic or -ous, depending on the name of the anion3) if the anion name ends in -ate, the suffix -ic is added to the root name 4) if the anion name ends in -ite, the -ite is replaced by -ous
