| A | B |
|---|
| element | substance that cannot be broken into simpler substances |
| compound | substance that can be broken into simpler substances |
| Robert Boyle | first to describe substances as elements or compounds |
| Antoine Lavoisier | discovered law of conservation of mass and identified 33 elements |
| J J Berzelius | devised modern system to symbolize names of elements |
| aluminum | Al |
| antimony | Sb |
| argon | Ar |
| arsenic | As |
| barium | Ba |
| beryllium | Be |
| bismuth | Bi |
| boron | B |
| bromine | Br |
| cadmium | Cd |
| calcium | Ca |
| cesium | Cs |
| chlorine | Cl |
| chromium | Cr |
| cobalt | Co |
| copper | Cu |
| fluorine | F |
| gallium | Ga |
| germanium | Ge |
| gold | Au |
| helium | He |
| hydrogen | H |
| iodine | I |
| iron | Fe |
| krypton | Kr |
| lead | Pb |
| lithium | Li |
| magnesium | Mg |
| manganese | Mn |
| mercury | Hg |
| neon | Ne |
| nickel | Ni |
| nitrogen | N |
| oxygen | O |
| phosphorous | P |
| platinum | Pt |
| silicon | Si |
| silver | Ag |
| sodium | Na |
| strontium | Sr |
| sulfur | S |
| tin | Sn |
| tungsten | W |
| zinc | Zn |
| carbon | C |
| americium | Am |
| astatine | At |
| berkelium | Bk |
| bohrium | Bh |
| californium | Cf |
| curium | Cm |
| einsteinium | Es |
| europium | Eu |
| fermium | Fm |
| francium | Fr |
| mendelevium | Md |
| neptunium | Np |
| nobelium | Nb |
| plutonium | Pu |
| potassium | K |
| radium | Ra |
| thorium | Th |
| uranium | U |
| xenon | Xe |
| metals | elements found on the left side of the periodic table |
| nonmetals | elements found on the right side of the periodic table |
| metalloids | elements found in the diagonal line between the metals and nonmetals in the periodic table |
| periods | horizontal rows of elements in the periodic table |
| families | vertical rows of elements in the periodic table |
| diatomic molecules | elements that naturally occur as pairs of combined atoms at room temperature |
| conductivity | ability of an element to transmit heat or electricity |
| luster | property of metals whose polished surfaces reflect light |
| malleability | property of metals to be hammered or rolled into thin sheets |
| ductility | property of metals to be drawn into wires |
| brittleness | property of nonmetals to be crushed when hit |
| Democritus | Greek philosopher proposed that matter is made of small indivisible particles |
| Aristotle | Greek philosopher proposed that matter was continuous and could be divided endlessly into smaller portions |
| Joseph Priestly | discovered oxygen when he focused sunlight on a mercury oxygen compound |
| Joseph Proust | proposed that specific compounds are always made of the same elements in definite proportions |
| law of definite proportions | compounds always contain elements in definite proportions |
| law of constant composition | compounds always contain elements in definite proportions |
| electrolysis | use of electricity to decompose (break down) substances into their component elements |
| John Dalton | first to propose the modern concept of atoms |
| subatomic particles | smaller components that make up atoms |
| electron | negatively charged subatomic particle |
| proton | positively charged subatomic particle |
| neutron | uncharged subatomic particle |
| nucleus | central part of atom containing protons and neutrons |
| mass of a proton | 1 amu |
| mass of a neutron | 1 amu |
| mass of an electron | $ \frac {1}{1837} $ amu |
| isotopes | atoms of the same element that have different masses |
| tritium | isotope of hydrogen with mass number of 3 (1 proton and 2 neutrons) |
| deuterium | isotope of hydrogen with mass number of 2 (1 proton and 1 neutron) |
| protium | isotope of hydrogen with mass number of 1 (only 1 proton) |
| atomic mass (atomic weight) | average mass of an element based on the average weights of element and all its isotopes |
| Avogadro’s number | $6.022 x 10^23$ |
| mole | amount of substance with Avogadro’s number of particles |
| molar mass | mass of $6.022 x 10^23$ particles of a particular substance expressed in grams |
