nature of chemical bonds

chemical bonds

• hold atoms together (usually in molecules or compounds)

• type examples: ionic bonds and covalent bonds

ionic bonds

• formed by an attraction of oppositely charged ions (usually metal and nonmetal)

• gain or loss of electrons forms ions

• electrical attraction of water molecules can disrupt forces holding ions together (because of its POLARITY)

covalent bonds

• from when atoms share 2 or more valence electrons (nonmetal and nonmetal)

• strength of a covalent bond depends on the # of shared electrons (the bond becomes shorter with strength)

electronegativity

• atom’s affinity for electrons/the uneven pull on electrons

• differences can dictate how electrons are distributed in covalent bonds

• inc. left to right on the periodic table (fluorine is the most)

nonpolar covalent bonds

• equal sharing of electrons

• no unfair pulling of electrons

polar covalent bonds

• unequal sharing of electrons

• can also go in hand with electronegativity

chemical reactions

• involve the formation or breaking of chemical bonds

  • atoms shift from one molecule to another without any change in number/identity of atoms

reactants

original molecules

products

molecules resulting from reaction

speed of chemical reactions

• can be influenced by: temperature, concentration of reactants and products, catalysts

temperature

• heating reactants inc. rate of reactions

• reactants collide w/ one another more often

concentration of reactants and products

reactions happen more quickly the more there are since there will be more frequent collisions

catalysts

a substance that inc. the rate of the reaction

• doesnt alter equilibrium

rutherford scattering experiment

• carried out in early 20th century

• revealed physical nature of atoms

• proposed the existence of a nucleus

isotopes

• atoms of a single element that posses different numbers of NEUTRONS

radioactive isotopes

an isotope that is unstable and undergoes radioactive decay, releasing energy as the nucleus breaks up

half life

time is takes for one-half of the atoms in the sample to decay

electron arrangement

• key to the chemical behavior of an atom

• the number and arrangement of its electrons in their orbitals

bohr model

electrons in discrete orbits

energy levels

• electrons have potential energy related to their position

• electrons farther from nucleus have MORE energy

redox

electrons can be transferred from one atom to another during chemical reactions

• still retain the energy of their position in the atom

oxidation

loss of an electron

reduction

gain of an electron