Anita Akweshie-
definition of a transition element
a d block element that can form one or more stable ions of variable oxidation states with an incomplete d subshell
-
what are the metals in the d block that are not included in the classification of transition elements
scandium and zinc
-
why is scandium not classed as a transition element
only forms one ion of 3+
has no electrons in the d subshell
-
why is zinc not classed as a transition element
only forms one ion of 2+
has a complete d subshell
-
all transition elements have
incomplete d subshells
-
what are the 5 d orbitals
3dyz
3dxz
3dxy
3dx2 - y2
3dz2
-
what do the orbitals 3dyz, 3dxz, and 3dxy have in common
they all have four lobes that point between the axes
-
what does a 3dx2 - y2 orbital look like
the four lobes point along the two axes and not between them
-
what does a 3dz2 orbital look like
the are two main lobes that point along the z-axis and a doughnut ring around the center
-
what properties do transition elements have different from normal metals
variable oxidation states
behave as catalysts
form complex ions
form coloured compounds
-
what kind of ions are formed by transition elements
positively charged cations
-
what is meant by variable oxidation states
an element can exist in more than one stable oxidation ionic state
-
what is put in the name of transition compound to show the oxidation state of the transition element
roman numerals
-
what are the common oxidation states of Titanium (Ti)
+3, +4
-
what are the common oxidation states of Vanadium (V)
+2, +3, +4, +5
-
what are the common oxidation states of Chromium (Cr)
+3, +6
-
what are the common oxidation states of Manganese (Mn)
+2, +4, +6, +7
-
what are the common oxidation states of Iron (Fe)
+2, +3
-
what are the common oxidation states of Nickel (Ni)
+2
-
what are the common oxidation states of Copper (Cu)
+1, +2
-
why can transition elements act as catalysts
during catalysis the T.E can change to various oxidation states by gaining or donating electrons from reagents with vacant d orbitals and adsorbance can take place on their surfaces
-
what is another feature caused by their ability to form variable oxidation states
the ability to form complex ions
-
what is a complex ion
a molecule or ion consisting of a central metal atom or ion with a number of molecules or ions surrounding it
-
what are ligands
the molecules or ions surrounding the central metal atom or ion that have one or more lone pairs of electrons
-
what happens to the central metal ion concerning ligands due to the different oxidation states of the central metal atoms
can be bonded to a different number and wide variety of ligands
-
why is the most common oxidation state +2
the first two 4s electrons are lost
-
why are transition metals more towards the end of the period more likely to adopt the +2 oxidation state as their highest state
the 3d electrons become slightly harder to remove as the nuclear charge increases due to 3d electrons being more strongly attracted to the nucleus and higher oxidation states become less stable and so are more likely to lose 4s electrons only
-
how can a transition element adopt more than one stable oxidation state
can lose or gain electrons easily to go from one oxidation state to another
-
how can transition elements catalyse redox reactions
act as both oxidising and reducing agents
-
the higher the oxidation state of the transition elements, the more powerful the
oxidising agent
-
what can the availability of vacant d orbitals of transition elements mean for bond formation
dative bonds can be formed between the transition elements and the ligands from the ligand into the vacant d orbitals
-
what are the possible overall charges of complex ions
positive, negative or neutral
-
what is a charged complex called
a complex ion
-
what are complexes formed from
central metal ions and ligands
-
what are examples of neutral ligands
water and ammonia
-
where is the lone pair donated from in the water molecule
the oxygen atom
-
where is the lone pair donated from in the ammonia molecule
the nitrogen atom
-
what is the coordination number of a complex
the number of dative bonds formed between the central atom and the ligands
-
what is the coordination number of a complex formed with water ligands
6
-
what is the shape of complexes with a coordination number 6
octahedral shape
-
what is the overall charge of a complex with cobalt (II) or copper (II) as a central metal ion and water or ammonia molecules as ligands and why
+2 because the ligands are neutral and the metal ion has a +2 charge
-
what are examples of negatively charged ligands
hydroxides and chloride ions
-
what are examples of small ligands
water
ammonia
hydroxide
-
what are examples of large ligands
chloride
-
how many small ligands can fit around a central metal ion
6
-
how many large ligands can fit around a central metal ion
4
-
what shape do complexes with coordination number 4 make
tetrahedral complexes
-
what are examples of ligands
water
ammonia
chloride
cyanide
thiocyanate
ethanedioate (ox)
1,2-diaminoethane (en)
-
Ture or False
different ligands can form different numbers of dative bonds to the central metal ion
true
-
what is a monodentate ligand
a ligand that can only form one dative bond to the central metal ion
-
what are examples of monodentate ligands
water (H2O) molecules
ammonia (NH3) molecules
chloride (Cl-) ions
cyanide (CN-) ions
-
what are bidentate ligands
each ligand can form two dative bonds to the central metal ion
-
what are examples of bidentate ligands
1,2-diaminoethane (en)
ethanedioate ion (ox)
-
what are polydentate ligands
these are ligands that contain more than two atoms with lone pairs of electrons to form more than two dative bonds to the central metal ion
-
what is an example of a polydentate ligand
EDTA4-
-
complexes have different geometries depending on
the size of the ligands and the number of dative/coordinate bonds to the central metal ion
-
central metal ions with two coordinate bonds form what geometry and bond angle with ligands
linear and angle 180
-
what are examples of linear complexes
copper (I) or silver (I) ions and two ammonia ligands
-
central metal ions with four coordinate bonds sometimes form what geometry and bond angle
tetrahedral shape and 109.5
-
what type of ligands form tetrahedral geometries
4 chloride ions
-
complexes with four coordinate bonds other times form what geometry and bond angles with ligands
square planar and 90
-
what type of ligands form a square planar complex
cyanide ions
-
what is an example of a square planar complex
cisplatin
-
complexes with six coordinate bonds form what geometry and what bond angles
octahedral and 90
-
how many ways could the six coordinate bonds of an octahedral complex be formed
3
-
type 1 of octahedral complexes
six coordinate bonds formed by six small monodentate ligands
-
examples of type 1 octahedral ligands
water molecules
ammonia molecules
hydroxide ions
thiocyanate ions
-
type 2 of octahedral complexes
six coordinate bonds with three bidentate ligands that each form two dative bonds
-
examples of type 2 octahedral complexes
1,2-diaminoethane ion
ethanedioate ion
-
type 3 of octahedral complexes
six coordinate bonds formed by one polydentate ligand
-
examples of type 3 octahedral complexes
EDTA4-
-
what determines the coordinate number
the number of coordinate/dative bonds
-
what do you need to predict the formula nd charge of a complex ion
the central metal ion and its charge/oxidation state
the ligands
the coordination number/geometry
