unit 1 section 3 bonding Flashcards
what is an ionic bond
it is a bond between two oppositely charge ions. held by electrostatic forces of attraction. this is normally a bond between a metal and a non metal
what is the ionic formula for ammonium
NH^4
what is the formula for ammonia
NH^3
what is the ionic formula for carbonate
CO^2-, 3
what is the ionic formula for an hydroxide
OH-
what is the ionic formula for a nitrate
NO^- , 3
what is the ionic formula for sulfate
SO^2- , 4
what does electrostatic forces do and are they strong
they hold positive and negatively charged ions together. they are strong bonds
what is a cation
a positive ion
what is an anion
it is a negative ion
what is a lattice
it is a regular structure
why are giant lattices giant
they are giant because they are made up of the same repeating unit
give an example of a giant lattice
MgO , NaCl
what is the electrical conductivity behavior of ionic compounds
they conduct electricity when they are molten or dissolved but not when they are solid
what is the melting point of ionic compounds
they have high melting points, this is because they are held together by strong electrostatic forces of attraction.
what is the behavior of solubility in ionic compounds
tend to dissolve in water. water bonds are polar and they pull ions away from the lattice causing it dissolve.
what is a simple covalent compound
it is a compound that is made up of lots of individual molecules.
what force holds atom in a molecule
covalent bonds
what bond holds molecules within a simple covalent compound
weak intermolecular forces of attraction
how are the carbon atoms in graphite arranged
the carbon atoms are arranged in sheets of hexagons that are covalently bonded to each other
how are the sheets of flat hexagons in graphite boned between layers
the fourth outer electron on each carbon is delocalised and the sheets are bonded by weak van der waals forces
what are the properties of graphite
- weak bonds in graphite layer is easily broken, allows layers to slide over each other
- delocalised electron can move freely, therefore graphite can carry a charge/ a current can flow.
- high melting points due to strong covalent bonds
- insoluble in any solvent
what are the properties of diamond
- high melting point
- extremely hard
- good thermal conductor, vibrations travel through it easily
- cannot conduct electricity
- cannot dissolve in any solvent
what is a co-ordinate / dative bond
it is when the bonding electrons comes from one atom
what are lone pairs of electrons
electrons that are unshared / not bonded
what is a charge cloud
it is an area in which an electron can exist.
what repels more, lone pair charge clouds or bonding pairs
lone pairs
what is the valence shell electron repulsion theory
it is the theory that lone pair electrons repel more than bonding pair electrons, this causes the bond angles to reduce as the lone pair repels the bonding pairs closer to each other
how do you work out the number of electron pairs and bonding pairs and lone pairs
central atom group + bonds +charge / 2
- compare to how many bonds you have to the number you get bonding pairs to lone pairs
what is the shape and bond angle of a central atom with two bonding pairs
linear , 180
what is the shape and bond angle of central atom with three bonding pairs
trigonal planar , 120
what is the shape and bonding angle of a central atom with two bonding pairs of electrons and one lone pair of electrons
bent , 117.5
how much does 1 lone pair reduce the bond angle by
2.5 degrees
what is the shape and bond angle of a central atom with four electron pairs
tetrahedral , 109.5
what is the shape and bond size of a central atom with 3 bonding pairs and one lone pair
trigonal pyramidal , 107
what is the shape and bond angle of a central atom with 2 boning pairs and 2 lone pairs
bent , 104.5
what is the shape and bond angle of a central atom with 5 bonding pairs
trigonal bipyramidal , 120 & 90
what is the shape and bond angle of a central atom with 4 bonding pairs and 1 lone pair
seesaw , 86.5
what is the shape and bond angle of a central atom with 6 bonding pairs
octahedral , 90
what is the shape and bond angle of a central atom with 4 bonding pairs and 2 lone pairs
square planar , 90
what is electronegativity
it is the ability to attract the bonding pair of electrons in a covalent bond.
what is electronegativity measured in
it is measured in the Pauling scale
what is the most electronegative element
fluorine
are diatomic gases bond polar
they are not polar as they have the same electronegativity. the electrons are equally attracted to the both nuclei
what is a polar bond
it is a bond between two atoms that have different electronegativities. the atoms with the higher electronegativity pulls the electrons closer to that atom, this makes the bond polar as the electrons are not spread out evenly.
what is a dipole
a dipole is a difference in charge between two atoms caused by a shift in electron density in the bond
what is a polar molecule
it is a molecule that has a permanent dipole because the charge is unevenly distributed
how do you know if a molecule has an overall permanent dipole
whether the molecule has a permanent dipole depends on the shape of the molecule, it depends on whether the bonds are arranged symmetrically and the dipoles cancel each other out.
what are intermolecular forces
they are forces between molecules. they are weaker than covalent bonds
what are the three types of intermolecular forces of attraction
hydrogen bonding, permanent dipole-dipole , van der waals ( induced dipole-dipole)
explain how an induced dipole-dipole bond works
electrons in a charge cloud move really fast and at any particular moment in time the electrons can be found more to one side than the other, this causes a temporary dipole in the atom. this dipole can cause another dipole in the other direction in a neighboring atom. the two dipoles are attracted to each other, the second dipole can cause another dipole in a third atom.
why do larger molecules have stronger van der waals
they have stronger van der waals because they have larger charge clouds which means they have stronger van der waals.
what is permanent dipole forces
this is forces between molecules that have permanent dipoles. the weak electrostatic forces between the δ+ and the δ- charges on the neighboring molecules causes the permanent dipole
what is the difference between induced dipole-dipole and a permanent dipole force
induced dipole is between atoms and the permanent dipole is between molecules.
what is the strongest intermolecular force
hydrogen bonding
what is hydrogen bonding
it is a bond between hydrogen and either nitrogen, fluorine and oxygen. these 3 elements are very electonegative so they draw bonding electrons away from the hydrogen atom.
what affect does hydrogen bonding have on the properties on substances
have higher boiling and melting point due to the amount of energy needed to overcome the hydrogen bond.
explain why melting point of metallic bonded molecules is high
they have high melting points due to the strong electrostatic forces of attraction between the positively charged metals ions and the negatively charged sea of delocalised electrons. the number of electrons per atom affects the melting point, the more the stronger the bonding and the higher the melting point will be
why are metals easy shaped
they can be easily shaped as there are no specific bonds holding ions together, so therefore they can slide over each other.
are metals soluble
they are insoluble except in liquid metals due to the strength of the metallic bonds.