Bonding Flashcards
How do you draw a dot and cross diagram
You draw the electron shells of the metal (giving the electron(s)) and draw it after the bonding process - all electron shells are filled and it has less electrons than normal since it just gave some electrons (draw these electrons with dots/crosses)
You draw the non metal with crosses (or dots if you alr did crosses) and then include all the shells/electrons and for the electron given by the metal you draw it as however you drew the metal
you then put 2 big brackets around each one and put the charge on top (right)
Explain how ionic bonds are formed by the transfer of electrons
between atoms to produce cations and anions
● Metals + nonmetals: electrons in the outer shell of the metal atom are transferred
o Metal atoms lose electrons to become positively charged ions (cation)
o Nonmetal atoms gain electrons to become negatively charged ions (anion)
Recall that an ion is an
atom or group of atoms with a positive or negative charge
What does the group number have to do with the ionic charge when the element is charged
IE: Group 1 atoms will lose 1 electron and gain +1 charge
Group 2: +2 charge
Group 4 will not bond ionically
What do the endings ide and ate mean
-ide means the compound contains 2 elements (one is the nonmetal -ve ion)
-ate means the compound contains at least 3 elements, one of which is oxygen
Halide ->
involves a -1 halide ion (e.g. sodium chloride NaCl)
● Nitrate ->
involves NO3 1- ion (e.g. sodium nitrate: NaNO 3 )
Carbonate ->
involves CO3 2- ion (e.g. sodium carbonate: NaCO 3 )
● Sulfate ->
involves SO4 2- ion (e.g. sodium sulfate: NaSO 4 )
Explain the structure of an ionic compound as a ______ structure: consisting of a _______ ____________ of ions; held together by _______ _____________ ______ (ionic bonds) between _______ __________ ions
lattice
regular arrangement
strong electrostatic forces
oppositely charged
Explain how a covalent bond is formed when
a pair of electrons is shared between two atoms
ie: Hydrogen and chlorine can bond covalently to form hydrogren chloride as hydrogen can share its 1 electron and match with the other electron missing (as they are grouped in pairs when you draw them) to form the 2nd electron filling out the shell
Recall the typical size (order of magnitude) of atoms and small molecules
Atoms typically have a size of about 10^-10 meters (0.1 nanometers),
while small molecules are in the same range, around 10^-10 to 10^-9 meters (0.1 to 1 nanometers).
How do you drwa a covalent bond
Draw the 2 elements in a venn diagram kind of shape, you only use the outer shell and you put the shared electrons (represented with dots and crosses) in the centre of the venn diagram kinda
ie: carbon needs 4 electrons to fill the outer shell and oxygen needs 2 so you draw carbon in the middle with each oxygen overlapping the carbon on the opposite sides). You put 2 electrons in the middle of each overlap (oxygen) and 2 aswell for carbon for each. You then place the other oxygen electrons in the outer shell somewhere on there.
Recall that most metals are ________ ______ and that their typical properties include:
transition metals
high melting point
high density
the formation of coloured compounds
catalytic activity of the metals and their compounds
as exemplified by iron
Explain, using models, why converting pure metals into alloys often increases the strength of the product
Alloys will have some elements as large balls and some as small balls (in a diagram) as there are different sized atoms
This distorts the regular lattice structure, so layers of atoms cannot slide over each other so easily.
Malleable
can be hammered into sheets
ductile
can be drawn into wires
lustrous
shiny when polished or freshly cut
Explain why iron is alloyed with other metals to produce alloy steels
it significantly enhances its properties, making it stronger, harder, and more durable for various applications.
Explain how the uses of metals are related to their properties, including aluminium, copper and gold and their alloys including magnalium and brass
aluminium: low density, used for aircraft
copper: good conductor, used in electrical cables
gold: good resistance to corrosion, used in jewelry
magnalium (aluminum + magnesium): low density, used in cars and planes
brass (copper + zinc): hard, resistant to corrosion, used in coins
Properties of ionic compounds
● Ionic compounds are made up of a metal and a nonmetal
● Ionic compounds have regular structures (giant ionic lattices) in which there are strong electrostatic forces of attraction between oppositely charged ions.
● They have high melting and boiling points , because a lot of energy is required to break the many strong bonds.
● When melted or dissolved in water, ionic compounds conduct electricity because the ions are free to move and carry current, and they do not conduct electricity as solids, because the ions are fixed and are not able to move, carrying charge with them.
● Often dissolve in water to form an aqueous solution
Properties of simple molecular compounds (covalent)
low boiling and melting points .
● Substances that consist of small molecules have weak intermolecular forces
○ The intermolecular forces increase with the size of the molecules, so larger molecules have higher
melting and boiling points.
● Substances that consist of small molecules don’t conduct electricity
● Many are insoluble in water, but some are soluble
Properties of giant covalent structures
They are made up of nonmetal elements
● Substances that consist of giant covalent structures are solids with very high melting points .
o All of the atoms in these structures are linked to other atoms by strong covalent bonds.
▪ These bonds must be overcome to melt or boil these substances.
● some giant covalent structures can conduct electricity , whereas others can’t
Properties of metals
● Metals consist of giant structures of atoms arranged in a regular pattern. They are always made up of just metallic elements
● The electrons in the outer shell of metal atoms are delocalised and so are free to move through the whole structure.
● The sharing of delocalised electrons gives rise to strong metallic bonds.
Recall that graphite and diamond are….
and that they are examples of…
different forms of carbon
giant covalent structures
Describe the structures of diamond
● In diamond, each carbon is joined to 4 other carbons covalently.
o It’s very hard, has a very high melting point and does not conduct electricity.
describe the structure of graphite
Graphite
● In graphite, each carbon is covalently bonded to 3 other carbons
o The layers can slide over each other due to no covalent bonds between the layers, but weak intermolecular forces. Meaning that graphite is soft
and slippery.
● One electron from each carbon atom is delocalised.
o This makes graphite similar to metals, because of its delocalised electrons.
o It can conduct electricity – unlike diamond.
Explain, in terms of structure and bonding, why graphite is used to make electrodes and as a lubricant, whereas diamond is used in cutting
tools
● Graphite uses
o Electrodes – graphite can conduct electricity – unlike Diamond
o Lubricant – weak intermolecular forces and no covalent bonds between the layers, therefore it is soft and slippery
● Diamond uses
o Cutting tools – very hard, due to its rigid structure
Explain the properties of fullerenes including C 60 and graphene in terms of their structures and bonding
Graphene
o Single layer of graphite
o Has properties that make it useful in electronics and composites
● Carbon can also form fullerenes with different numbers of carbon atoms.
o Molecules of carbon atoms with hollow shapes
o The first fullerene to be discovered was Buckminsterfullerene (C 60 ), which
has a spherical shape
● Carbon nanotubes
o Cylindrical fullerenes with very high length to diameter ratios
o Their properties make them useful for nanotechnology, electronics and
materials
What are the limitations of dot and cross diagrams
they dont show how the ions are arranged in the space
What are the limitations of 3d models of ionic compounds
A 3D construction model still has limitations:
it is not to scale
it gives no information about the forces of attraction between the ions, or the movement of
electrons to form the ions
What are the limitations of 2d models of ionic compounds
it does not show where the ions are located on the other layers. This is important because there are different possible arrangements of ions.
Describe most metals as _____ solids which have high _____ ________, high ______ and are good ________ ___ _________ whereas most nonmetals have low _____ ________ and are poor _______ ___ __________
shiny
melting points
density
conductors of electricity
boiling points
conductors of electricity
