Question | Answer |
believed all matter was composed of 4 elements: earth, air, fire, and water | Greeks (400 B.C.) |
tried to turn cheap medals into gold | Alchemists (400 B.C. - 1600 A.D.) |
was the first chemist to perform truly quantitative experiments | Boyl (1600s) |
discovered oxygen | Priestly (1700) |
is often called the father of modern chemistry. | Lavosier (1700s) |
discovered the law of conversation of mass which says that matter is neither created nor destroyed | Lavosier (1700s) |
discovered the law of definite proportion | Proust (1700s) |
the law of definite proportion | a compound has a constant composition |
discovered the law of multiple proportions | Dalton (1700s) |
when Dalton's Atomic Theory was created | 1808 |
1st point of Dalton's Atomic Theory | all elements are composed of atoms which are indivisible and indistinctible particles |
2nd point of Dalton's Atomic Theory | atoms of the same element are identical. The atoms of any one element are different from those of any other. |
3rd point of Dalton's Atomic Theory | compounds are found by the joining of atoms of different elements |
4th point of Dalton's Atomic Theory | chemical reactions occur when atoms are separated, joined, or rearranged |
did gas experiments which have chemists the key for determining chemical formulas | Gay-Lussac (1800s) |
added large amounts of electrical energy to small quantities of gases in tubes | J.J. Thomson |
tubes where large amounts of electrical energy to small gases were in | cathode-ray tubes |
showed that cathode-rays are attracted to metal plates that have a positive electrical charge | J.J. Thomson |
believed that cathode-rays were actually a stream of negatively charged particles which he called electrons | J. J. Thomson |
a stream of negatively charged particles | electrons |
determined the change-to-mass ratio of an electron | J.J. Thomson |
discovered the electron | J.J. Thomson |
developed the plum pudding model of the atom | J.J. Thomson |
discovered the charge on an electron | Millikan |
calculated the mass of the electron to be 1/1840 the mass of a hydrogen atom | Millikan |
student of Thomson | Rutherford |
discovered protons | Rutherford |
developed the nuclear model of the atom | Rutherford |
predicted the existence of neutrons | Rutherford |
has virtually the same mass as the proton but no charge | neutrons |
have a positive charge equal in magnitude to the electron's negative charge | protons |
is the number of protons in an atom | atomic number |
z | atomic number |
each element has a unique _____ | atomic number |
is the number of electrons in a neutral atom | atomic number |
sum of the protons and neutrons | mass number |
a | mass number |
mass of an atom | mass number |
subtract the atomic number from it and you get the number of neutrons in the atom | mass number |
atoms with the same # of protons but different # of neutrons | isotopes |
most are produced artificially | isotopes |
most do not exist naturally | isotopes |
most common isotope of hydrogen | hydrogen-1 or hydrogen |
hydrogen-2 | deuterium |
hydrogen-3 | tritium |
the smallest electrically neutral unit of a substance that still has the properties of the substance | molecule |
are made up of two or more atoms bonded together | molecule |
examples of molecules | O2, O3, CH4, H2O, CO2 |
compounds composed of molecules | molecular compounds |
tend to have low melting points and boiling points | molecular compounds |
exist as gases or liquids at room temperature | molecular compounds |
most are compounds of atoms of two or more nonmetals | molecular compounds |
seven diatomic elements | hydrogen, fluorine, chlorine, bromine, iodine, oxygen, nitrogen |
color of chlorine | green |
color of bromine | reddish brown |
color of iodine | violet |
are the "shorthand" that chemists use to describe compounds | chemical formulas |
represent the combination of a substance | chemical formulas |
consist of chemical symbol and subscripts | chemical formulas |
represent the elements present in the substance | chemical symbols |
represent the ration of elements present | subscripts |
3 types of chemical formulas | empirical, molecular and structural |
represents the simplest ratio in which the atoms combine | empirical |
its subscripts are reduced | empirical |
represents the actual ratio in which the atoms combine | molecular |
gives the total # of atoms of each element present in the molecule | molecular |
is sometimes also the empirical formula | molecular |
shows the way atoms are joined together in a molecule | structural |
are atoms or groups of atoms that have a positive or negative charge | ions |
tend to form positive ions by losing one or more electrons | metallic elements |
tend to form negative ions by gaining one or more electrons | ions |
any atom or group of atoms that has a positive charge | cation |
has more protons than electrons | cation |
any atom or group of atoms that has a negative charge | anion |
has more electrons than protons | anion |
its name ends in -ide, ite, or ate | anion |
tightly bound group of atoms that behave as a unit and carries a charge | polyatomic ion |
ionic compound | salt |
composed of cations and anions | ionic compounds |
are electrically neutral | ionic compounds |
their total + charge = their total - charge | ionic compounds |
usually solids at room temperature | ionic compounds |
most are composed of metals and nonmetals | ionic compounds |
elements are arranged in order of increasing atomic number | periodic table |
elements are arranged in order of | increasing atomic number |
horizontal rows | periods |
the properties of the elements change as you move across a | period |
the patterns of properties within a _____ repeats when you move from one ____ to the next | period |
vertical rows | groups or families |
the elements in each ____ have similar chemical and physical properties | group |
group 1A | alkali metals |
very active metals that form +1 ions when reacted with nonmetals | 1A |
group 2A | alkaline earth metals |
form +2 ions when reacted with nonmetals | 2A |
group 7A | halogens |
form -ions when reacted with metal | 7A |
group 8A | nobles gases |
tend to exist as isolated atoms | 8A |
do not react readily with other elements | 8A |
are monatomic | 8A |
are the representative elements | group a |
they exhibit a wide range of physical and chemical properties | group a |
consists of the transition metals and the inner transition metals | group b |
3 classes of elements | metals, nonmetals, metalloids |
properties: high electrical conductivity, high luster, ductile, malleable | metal |
properties: low electrical conductivity, low luster, some are gases, some are brittle solids | nonmetals |
B, Si, Ge, As, Sb, Te, Po, At | metalloids |
name given to the empirical formula of an ionic compound | formula unit |
shows the lowest whole # ratio of ions | formula unit |
its total + charge = total - charge | formula unit |
contain 2 elements | binary ionic compounds (type 1) |
are composed of 2 different nonmetallic elements | binary molecular compounds |
binary covalent compounds | binary molecular compounds |
compounds that produce H+ ions when dissolved in water | acids |
hydrochloric acid | HCl |
sulfuric acid | H2SO4 |
nitric acids | HNO3 |
mass is neither created nor destroyed | low of conservation of mass |
a given compound always contains exactly the same proportion elements | law of definite proportion |
a law stating that when two elements form a series of compounds, the ratios of masses of the second element that combine with one gram of the first element can always be reduced to small whole numbers | law of multiple proportions |
the weighted average mass of the atoms in a naturally occurring element | atomic weights |
equal volumes of gases at the same temperature and pressure contain the same number of particles | Avogadro's hypothesis |
the "rays" emanating from the negative electrode (cathode) in a partially evacuated tube; a stream of electrons | cathode-ray tube |
a negatively charged particle that moves around the nucleus of an atom | electron |
the spontaneous decomposition of a nucleus of an atoms | radioactivity |
an atom having a dense center of positive charge (the nucleus) with electrons moving around the outside | nuclear atom |
the small, dense center of positive charge in an atom | nucleus |
a positively charged particle in an atomic nucleus | protons |
a particle in the atomic nucleus with mass virtually equal to the proton's but with no charge | neutron |
atoms of the same element (the same number of protons) with different numbers of neutrons. they have identical atomic numbers but different mass numbers | isotopes |
the number of protons in the nucleus of an atom | atomic number |
the total number of protons and neutrons in the atomic nucleus of an atom | mass number |
the force or, more accurately, the energy, that holds two atoms together in a compound | chemical bond |
a type of bonding in which electrons are shared by atoms | covalent bond |
a bonded collection of two or more atoms of the same or different elements | molecule |
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 | chemical formula |
the representation of a molecule in which the relative positions of the atoms are shown and the bonds are indicated by lines | structural formula |
a model of a molecule showing the relative sizes of atoms and their relative orientations | space-filling model |
a molecular model that distorts the sizes of atoms but shows bond relationships clearly | ball-and-stick model |
an atom or group of atoms that has a net positive or negative charge | ion |
a positive ion | cation |
a negative ion | anion |
the electrostatic attraction between oppositely charged ions | ionic bond |
a solid containing cations and anions that dissolves in water to have a solution containing the separated ions which are mobile and thus free to conduct electrical current | ionic solid (salt) |
an ion containing a number of atoms | polyatomic ion |
a chart showing all the elements arranged in columns with similar chemical properties | periodic table |
an element that gives up electrons relatively easily and is lustrous, malleable, and a good conductor of heat and electricity | metal |
an element not exhibiting metallic characteristics. Chemically, a typical nonmetals accepts electrons from a metal. | nonmetal |
a vertical column of elements having the same valence electron configuration and showing similar properties | group (family) |
a group 1A | Alkali metals |
group 2A metals | alkaline earth metals |
a group 7A element | halogens |
a group 8A element | noble gases |
a two-element compound | binary compounds |
a substance that produces hydrogen ions in solution; a proton donor | acid |