Chemistry Review

Proton• positively charged part of an atom

– found in the nucleus– has mass– constant in every atom of an element

• Ex: every atom of oxygen has 8 protons

Neutron• part of an atom that has no charge

– found in the nucleus– has mass– may be different in different atoms of the same

element• Ex: an atom of carbon may have 6, 7, or 8 neutrons

Electron• negatively charged part of an atom

– has little to no mass– found outside of the nucleus

• determine how atoms react (interact) with other atoms

– may change in number when an atom interacts with other atoms• Ex: sodium (Na) normally has 11 electrons but often

loses 1

Ion• an atom that has lost or gained 1 or

more electrons and now has a charge– lose electron = positive ion– gain electron = negative ion

Ion

Ion

Isotope• atoms of the same element with different

numbers of neutrons– does not affect how the atom reacts with other

atoms

Ionic Bonds• attraction connecting atoms of

oppositely charged ions– bonds metals to nonmetals

Metals vs. Nonmetals

Ionic Bonds• attraction connecting atoms of

oppositely charged ions– bonds metals to nonmetals– one atom gives up 1 or more electrons to

another atom

Ionic Bonds

Ionic Bonds• attraction connecting atoms of

oppositely charged ions– bonds metals to nonmetals– one atom gives up 1 or more electrons to

another atom– form crystal lattices – patterned

structures of repeating ions

Crystal Lattice

Ionic Substances• substances made of oppositely charged

ions held together by ionic bonds– ex: table salt, rock (road) salt

Covalent Bonds• attraction connecting atoms that share 1

or more electrons– bonds nonmetals together– form molecules – individual groups of

atoms

Carbon Dioxide Molecules

Covalent Bonds• attraction connecting atoms that share 1

or more electrons– bonds nonmetals together– form molecules – individual groups of

atoms– the electrons are not always shared

equally

Molecules in Air(nitrogen [N2], oxygen [O2], water [H2O],

and carbon dioxide [CO2])

What is the difference between a crystal lattice and a molecule?Crystal Lattice

Sodium chloride

NaCl

Molecule

Carbon Dioxide

CO2

What is the difference between a crystal lattice and a molecule?

• In a crystal lattice, ions are interconnected as a part of a repeating pattern.– does not have a constant number of atoms– however, the ratio is always the same

• Ex: A TINY piece of salt may have 1,000 sodium atoms and 1,000 chlorine atoms. Another SLIGHTLY BIGGER piece of salt may have 1,500 sodium atoms and 1,500 chlorine atoms. In both pieces, the ratio of sodium atoms to chlorine atoms is 1-to-1.

What is the difference between a crystal lattice and a molecule?

• In a molecule, each group of atoms is only connected to the other atoms in that molecule.– the number of atoms of each element is

constant• Ex: Carbon dioxide molecules are ALWAYS made

of 1 carbon atoms and 2 oxygen atoms.

What is the difference between a crystal lattice and a molecule?Crystal Lattice

Sodium chloride

NaCl

Molecule

Carbon Dioxide

CO2

Nonpolar Covalent Substances• substances held together by covalent

bonds with equally shared electrons– no charged ends of the molecule– ex: methane, vegetable oil

Polar Covalent Substances• substances held together by covalent

bonds with unequally shared electrons– unequal sharing causes the molecule to

have charged ends – ex: water, sugar

What is the difference between a polar molecule and a nonpolar

molecule?

What is the difference between a polar molecule and

a nonpolar molecule?

• Nonpolar molecules do NOT have charged ends.

• Polar molecules HAVE charged ends.