chemistry unit 4 concept 1-2

electronegativity

a measure of the ability of an atom in a bond to attract electrons

molecule

compound formed when 2 or more elements are covalently bonded

salt

a binary ionic compound between one kind of metal atom and one kind of nonmetal atom

crystal lattice

network of cations and anions that are mutually attracted to one another

intermolecular

between different substances

intramolecular

within the same substances (chemical bonds)

why is bonding a spectrum?

there arent just two types of bonds. it is a spectrum with ionic and nonpolar covalent at the two extremes

what are the connections between chemical bonds, chemical reactions, and compounds?

chemical bonds form through chemical reactions and result in new compounds

why do most atoms form chemical bonds while some atoms dont?

they form bonds to be stable with full outer energy levels of electrons

noble gases dont form chemical bonds because they are already stable

what does the chemical formula tell you about an ionic compound?

represents the ratio of cations to anions in the crystal lattice

what does the chemical formula tell you about a covalent compound?

tells you exactly the number and types of atoms

ionic bonds

- electrons are transferred from the cation (positive) to the anion (negative)

- typically between a metal and a nonmetal

- always between ions

- can result in the formation of a salt

covalent bonds

- electrons are shared

- always between nonmetals

- can be polar or nonpolar

- results in the formation of a molecule

ionic compounds

- crystalline solids

- high melting and boiling points

- can conduct electricity when dissolved in water

- made up of positive and negative ions that chemically bond in a way that the charges equal out

covalent compounds

- can be solid, liquid, or gas

- low melting or boiling points

- cannot conduct electricity when dissolved in water

polyatomic ion

a positively or negatively charged, covalently bonded group of atoms

transition metal

metals that "transition" because they can form many different ions (charged atoms)

explain the difference between electronegativity and the formation of an ionic bond

the difference in electronegativity is so great that one atom takes electrons from another because it has such a greater attraction to them

example of a rule of zero charge with an ionic compound

MgCl2 is one atom of magnesium with a +2 charge and two atoms of chlorine with a -1 charge

binary ionic compound

made of two elements that transfer electrons in an ionic bond

compounds with polyatomic ions

made of one or more covalently bonded charged group of atoms that transfer electrons in an ionic bond

binary molecular compounds

made of two elements that share electrons in a covalent bond

why is it necessary to include a roman numeral when naming an ionic compound with a transition metal?

you cannot determine the charge of a transition metal from the periodic table, so the roman numeral is necessary to indicate the charge of the metal ion

an example of a common compound and how the properties of the elements that make it up are different than the compound itself

-NaCl = sodium chloride

- sodium on its own is extremely explosive when in contact with water

- chlorine on its own is very poisonous

- together they make table salt, which we can eat