Chapter 2 Flashcards
the types of attraction between molecules
intermolecular forces
intramolecular forces
intermolecular forces
forces that bond molecules together
also known as van der waals forces
intramolecular forces
forces that bond the atoms within a molecule together
involved in the formation of true chemical bonds
relative strength of inter and intra-molecular forces
intramolecular forces are 30-400x stronger than intermolecular forces
2 major and 1 minor types of bonding
major: ionic and covalent
minor: metalic
ionic bonding
bonding that involves yje transfer of electrons from 1 atom to anotehr to produce ions
resulting substances are held together by strong electrical attractions between + and - ions
forms ionic compounds (composed of metals and non metals) usually called salts or crystals
involves the transfer of electrons between valence shells of atoms
results in ionic compounds
ion
an atom or group of atoms that carries iether a positive or negative charge
cation: positive charge, gives up electrons, metal
anion: negative charge, takes electrons
formation of ionic compounds
ionic bonds form when one of the atoms is attracted to the electron pair much more strongly than the other atom, thus, the electron pair is pulled closer to that atom and away from the other
electronegativity
the ability of an element to attract electrons
properties of ionic compounds
- tend to form crystal lattices
-high m.p and b.p
-solid at room temp
low volatilities
-solid state is brittle
-solid has poor conductivity of both electricity and heat because ions cant move
-the liquid state has high conductivity as ions can move
why is H2 more stable than 2 H atoms
whenever a bond is formed enegru is released that makes the things involved more stable than they were originally. the more bonds an atom can form the more energy is released, and the more stable the system becomes. in the case of H, there is only 1 atom to share so it can only form 1 covalent bond. The H2 molecule is still much more stable than 2 H atoms
what gives substancs their phsyical propertiees
All elements have unique properties because of the bonding in the molecule, the result of this ranges form different boiling points, melting points to the ability to conducting electricity if there are electrons that can move.
what gives a susbtance its chemical properties
Chemical properties of matter describe its potential to undergo some chemical change or reaction by its composition. the electron configuration of the elements involved, and, if any, bonds present.
single bond
longest bond weakest bond
double bond
in between single and triple in terms of strength and length
triple bond
shortest bond, strongest bond
why does more than 1 bond form
when atoms bond covalently, they do so in a way that forms the most number of bonds possible so that the final molecule is as stable as possible
why is water more stable than 2 H and O
it costs energy to break bonds but a lot fo energy is released when new ones are made. the reaction between h and o is explosive. this is because more energy is released making new bonds than breaking old ones. because so much energy is released, H2O is more stable than a mixture of H and O
what happens when metal atoms bond toegther
the outer electrons on each metal atom become free to move throughout the whole structure, they become delocalised. as the atoms lose electrons, positively charged metal ions are left behind, the attraction between each positive ion and the sea of delocalised elctrons make metals as a whole very hard with high mp and bp
how do intermolecular forces arise
through sllight electrical distorions in molecules
intermolecular forces during melting
heating gives the moelcule enough energy so that the intermolecular attractions arent strong enough to keep the molecules in a solid structure. once in liquid state, there are temporary attractions between water molecules the molecules can move because these forces of attraction are being broken and remade all the time
intermolecular forces during boiling
attractions are totally disrupte dand the molecules become free to move around as gases. more heat makes the molecules move fast so the attractions cant hold them together anymore
