EL 4 - Inorganic Chemistry and the Periodic Table Flashcards
What is first ionisation enthalpy?
The enthalpy change that occurs when one mole of electrons is removed from one mole of gaseous atoms
What does the group (column) number represent in the periodic table?
The group number represents the number of electrons present in the outer shell of the atom
What does the period (row number) represent in the periodic table?
The period represents the number of electron shells in the atom
Why does first ionisation increase as we move across a period?
The number of protons in the nucleus increases which increases the nuclear charge and thus the nuclear force felt by outer electrons it therefore takes more energy to remove them
What is the formula of a nitrate ion?
NO3 -
What is the formula of a sulfate ion?
SO4 2-
What is the formula of a carbonate ion?
CO3 2-
What is the formula of a hydroxide ion?
OH -
What is the formula of an ammonium ion?
NH4 +
What is the formula of a hydrogencarbonate ion?
HCO3 -
What is the formula of a copper ion?
Cu 2+
What is the formula of a zinc ion?
Zn 2+
What is the formula of a lead ion?
Pb 2+
What is the formula of an Iron (II) ion?
Fe 2+
What is the formula of an Iron (III) ion?
Fe 3+
Why does the first ionisation energy decrease down a group?
The number of shells in the atom increases, which increases the shielding of outer electrons from the nucleus. The nuclear radius also increases. Both of these factors mean that the attractive nuclear force felt by the electron is smaller, so it takes less energy to remove outer electrons
How do the charge densities of group 2 ions affect the thermal stability of their carbonates?
Smaller ions with the same charge have higher charge densities and distort the carbonate ion, so that the compound will decompose at a lower temperature
How can we test for Fe 2+ ions?
Add OH- ions, the green solution will form a green precipitate
How can we test for Fe 3+ ions?
Add OH- ions, the yellow solution will form an orange precipitate
How can we test for Cu 2+ ions?
Add OH- ions, the blue solution will form a blue precipitate
How can we test for NH4 + ions?
Add NaOH(aq) to a boiling tube containing the NH4 + ions, warm the boiling tube. Any vapours given off by the tube will turn damp red litmus paper blue if NH4 + ions are present
How can we test for Al 3+ ions?
Add OH- ions, the colourless solution will form a white precipitate
How can we test for Cl- ions?
Add a few drops of HNO3, shake the test tube. Add a few drops of AgNO3, a white precipitate should form
How can we test for Br- ions?
Add a few drops of HNO3, shake the test tube. Add a few drops of AgNO3, a cream precipitate should form
How can we test for I- ions?
Add a few drops of HNO3, shake the test tube. Add a few drops of AgNO3, a yellow precipitate should form
How can we test for SO4 2- ions?
Add Ba 2+ ions, a white precipitate should form
How can we test for CO3 2- ions?
Add dilute nitric acid, if effervescence occurs then CO3 2- ions are present
How can we test for Li+, Na+, K+ and Ca+ ions?
Evaporate the water from the sample, moisten a test wire and collect the solid residue from the evaporating dish. Pass this residue into a bunsen burner and record the colour of the flame
Which ions show which colours in the flame test?
Na+ = Orange
Ca+ = Brick red
Li+ = Red
K+ = Lilac
Ba 2+ = Green
Cu 2+ = Blue-green
How can we test for Pb 2+ ions?
Add OH- ions, a white precipitate will form. Upon adding excess OH- ions, the precipitate will dissolve
