Term | Definition |
actinide series | in the periodic table, f-block elements from period 7 that follow element actinium |
alkali metal | group 1 elements, except for hydrogen, they are reactive and usually exist as compound with other elements |
alkaline earth metals | group 2 elements in modern periodic table and are highly reactive |
atomic radius | 1/2 the distance between adjacent nuclei |
electronegativity | indicates relative ability of an elements atoms to attract electrons in a chemical bond |
formula unit | simplest ratio of ions represented in an ionic compound |
group | vertical column of elements in the periodic table arranged in order of increasing atomic number, also called a family |
halogen | highly reactive group 17 elements |
inner transition metal | type of group B element that is contained in the f-block of periodic table and characterized by a filled outermost orbital and filled or partially filled 4f & 5f orbitals |
ion | atom or bonded group of atoms with a positive or negative charge |
ionization energy | energy required to remove an electron from a gaseous atom, generally increases in moving left to right across a period and decreases moving down a group |
lanthanide series | in the periodic table, the f-block elements from period 6 that follow the element lanthanum |
metal | element solid at room temperature; good conductor of heat and electricity and generally is shiny. most are ductile and malleable. |
metalloid | elements that has physical and chemical properties of both metals and nonmetals |
molar mass | mass in grams of one mole of any pure substance |
mole ratio | in a balanced equation the ratio between the numbers of moles of any 2 substances |
noble gas | extremely unreactive group 18 elements |
nonmetal | elements that are generally gases or dull, brittle solids that are poor conductors of heat and electricity |
octet rule | states that atoms gain, lose , or share electrons to acquire stable electron configuration of a noble gas |
period | horizontal row of elements in the modern periodic table |
periodic law | states that when elements are arranged by increasing atomic number, there is a periodic repetition of their properties |
representative element | elements from groups 1, 2, 13-18 in the modern periodic table, possessing a wider range of chemical and physical properties. |
transition elements | elements in group 3-12 of modern periodic table and further divided into transition metals and inner transition metals |
transition metal | elements in group 3-12 contained in d-block of periodic table and with some exceptions characterized by filled outermost s orbital of energy level n and filled or partially filled d orbital of n-1 |
valence electron | electrons in an atoms outermost orbitals determine chemical properties of an element. |