Chapter 2 Flashcards
who invented the periodic table?
Dmitri Mendeleev
how many elements are there?
about 100 (118)
groups (vertical columns) indicate what?
the number of electrons in the outer shell of an element
what do the periods indicate?
the number of shells an atom has
why do elements of the same group have similar properties?
they have the same number of electrons in their outer shell
how many electrons do group 2 elements have in their outer shell?
2
group 1 elements are…
alkali metals
group 7 elements are…
halogens
group 0 elements are…
noble gases
what do the properties of elements depend on?
the number of electrons they have in their outer shell
how are electrons arranged in the shells?
they always fill the first shell first
how to figure out the electronic configuration of an atom?
- the atomic number indicates the number of protons and therefore electrons
- the period indicates the number of shells of an atom
- e.g nitrogen has 7 electrons and is found in period 2 so its electronic configuration is 2,5
find the electronic configuration of sodium using groups and periods
- sodium is in period 3, so it has 3 shells occupied
- the first 2 shells must be full (2,8)
- sodium is in group 1 so it has 1 electron in its outer shell
- 2,8,1
what can elements be classified as?
metals and non-metals
metals are found on..
the left hand side of the periodic table
non metals are found on the..
right hand side of the periodic table
where are metals and non-metals separated?
they are separated by a zig-zag going from Boron to Astatine
properties of metals
- metals conduct electricity because they allow charge to pass through them easily
- metal oxides are basic (they will neutralise acids)
- metal oxides which dissolve will form solutions with a pH of more than 7
non-metals
- poor conductors of electricity
- non-metal oxides are acidic (they will neutralise bases)
- they dissolve in water to form solutions with a pH of less than 7
group 0
- noble gases are all inert, colourless gases
- inert - don’t react with much at all
why are noble gases inert?
it takes a lot of energy to add or remove electrons from a noble gas atom
ionic bonding
- atoms lose or gain electrons and become ions
- the oppositely charged ions are strongly attracted to one another by electrostatic attractions
simple ions form when…
atoms lose or gain electrons
negative ion
anion - gain electrons
positive ion
cation - lose electrons
ions
are charged particles
- can be single atoms or groups of atoms
the number of electrons lost or gained is the same as…
…the charge on the ion
if two electrons are lost…
the charge is 2+
if 3 electrons are gained…
the charge is 3-
how do metals become ions?
- they lose electrons to form positive ions (cations)
- they are in group 1,2 and 3
what type of ion do metals become?
cations (positive ions)
what type of ion do non-metals become?
anions (negative ions)
how do non-metals become ions?
- they gain electrons to form negative ions (anions)
- they are in group 5,6 and 7
what structure do ionic compounds have?
a closely packed lattice structure
how do group 1 elements form ions?
they lose 1 electron and become 1+ cations
how do group 2 elements form ions?
they lose 2 electrons and become 2+ ions
how do group 3 elements form ions?
they lose 3 electrons and become 3+ cations
how do group 5 elements form ions?
they gain 3 electrons and become 3- anions
how do group 6 elements form ions?
they gain 2 electrons and become 2- anions
ammonium
NH₄⁺
hydroxide
OH¯
nitrate
NO3-
sulfate
SO₄²-
carbonate
CO₃²⁻
hydrogen ion
H+
silver ion
Ag+
copper ion
Cu²⁺
iron ion
Fe2+
how many diatomic elements are there?
7
what are the diatomic elements?
- hydrogen
- nitrogen
- oxygen
- fluorine
- chlorine
- bromine
- iodine
can ionic compounds conduct electricity?
- they cant conduct electricity when they are solid
- they are able when tehy are melted or dissolved
why do ionic compounds have hight melting and boiling points?
the electrostatic attraction between the oppositely charged ions is very strong, and a lot of energy is needed to overcome the strong attraction
covalent bonding
atoms bond by sharing pairs of electrons
what is the force of attraction that forms covalent bonds?
strong electrostatic attraction between the negatively charged shared electrons (bonding pair) and the positively charged nuclei of the atoms
how are the elements arranged in the periodic table?
by atomic number
what is the name given to the rows in the periodic table?
Periods
what is the name given to the columns in the periodic table?
groups
name the type of structure that ionic compounds have
giant ionic lattice
which non-metal element can conduct electricity?
graphite
why can graphite conduct electricity?
only 3 of each carbons 4 outer electrons are used in bonds, so each carbon atom has 1 electron that’s delocalised
what is the overall charge of an ionic compound?
zero (neutral)
how are ions held together in a giant ionic lattice?
by the attraction between oppositely charged ions
why do ionic compounds have high melting and boiling points?
because a lot of energy is needed to overcome the strong attraction between the oppositely charged ions
give 3 examples of noble gases
helium
neon
argon
what does the group to which an element belongs correspond to?
the number of electrons it has in its outer shell
why do elements of the same group have similar properties?
because they all have the same number of electrons in their outer shell
why do metals and non-metals react together?
because metals become cations and non-metals become anions, and the oppositely charged particles re
what attraction results in ionic bonds?
electrostatic forces of attraction
what is the overall charge of an ionic compound?
zero
do ionic compounds conduct electricity?
no, but if you melt them or dissolve them in water they are able to conduct electricity
why does graphite have a high melting point?
the covalent bonds in the layers need loads of energy to break
is C60 a giant covalent structure?
no, it is made up of large covalent molecules
what are C60 fullerene molecules?
hollow spheres made up of 60 carbon atoms
why is C60 fullerene solid at room temperature?
because it is a large molecule, so the intermolecular forces between the molecules are strong
what are C60 molecules held together by?
by intermolecular forces, so they can slide over each other, so it is soft
why is C60 fullerene a poor conductor of electricity?
the delocalised electron of each carbon atom can’t move between the molecules
