Physics Flashcards
What are p-block elements?
Elements where the differentiating electron enters the p-orbital of the outermost shell
P-block elements include groups 13 to 18 in the periodic table.
How many groups are in the p-block?
6 groups (13 to 18)
Each group corresponds to the number of electrons that can occupy the p-subshell.
What elements constitute Group 16?
- Oxygen (8O)
- Sulphur (16S)
- Selenium (34Se)
- Tellurium (52Te)
- Polonium (84Po)
Group 16 is also known as the oxygen family or chalcogens.
What is the significance of the term ‘chalcogens’?
It means ‘ore forming’
Many metal ores are oxides or sulphides.
What percentage of air volume is composed of oxygen?
20.95%
Oxygen is the most abundant element on Earth.
What is the occurrence of sulphur in the Earth’s crust?
0.034% by mass
Mainly found in combined forms as sulphates and sulphides.
What elements constitute Group 17?
- Fluorine (9F)
- Chlorine (17Cl)
- Bromine (35Br)
- Iodine (53I)
- Astatine (85At)
Group 17 is known as halogens.
Why are halogens highly reactive?
Due to high electronegativities
They are not found in a free state.
What is the main source of chlorine in seawater?
Sodium chloride (NaCl)
Seawater contains chlorides, bromides, and iodides.
What are the main noble gases in Group 18?
- Helium (2He)
- Neon (10Ne)
- Argon (18Ar)
- Krypton (36Kr)
- Xenon (54Xe)
- Radon (86Rn)
All noble gases except radon occur in the atmosphere.
What is the general electronic configuration for Group 16 elements?
ns2np4
This configuration is crucial for understanding their chemistry.
What happens to atomic and ionic radii down the groups?
They increase due to an increase in the number of shells
Across periods, they decrease due to increased effective nuclear charge.
What is the trend of ionization enthalpy in groups 16, 17, and 18?
High ionization enthalpy that decreases down the group
Increases across periods with increasing atomic number.
What are the common oxidation states of Group 16 elements?
- -2
- +2
- +4
- +6
Oxygen typically shows -2, +2 in OF2, and -1 in peroxides.
What is the most electronegative element in the periodic table?
Fluorine
Halogens have very high electronegativity.
What is the anomalous behavior of oxygen attributed to?
- Small atomic size
- High electronegativity
- Absence of d-orbitals
These factors lead to unique properties compared to other group 16 elements.
What is the state of oxygen at room temperature?
Gas
Other group 16 elements are solids at room temperature.
What is the typical covalency of oxygen?
2
Other group 16 elements can exceed a covalency of four.
What defines the physical state of halogens at room temperature?
- Fluorine and chlorine are gases
- Bromine is a liquid
- Iodine is a solid
This reflects their molecular weights and interactions.
What is the bond dissociation enthalpy order for halogen molecules?
Cl—Cl > Br—Br > F—F > I—I
This indicates the strength of the bonds among halogens.
What is the electron gain enthalpy trend in groups 16 and 17?
Becomes less negative down the group
Smaller atomic size results in less negative values for oxygen and fluorine compared to their heavier counterparts.
What is the significance of the inert pair effect?
Stability of higher oxidation states decreases down the group
This effect explains the behavior of elements in groups 13 to 16.
What characterizes the chemical behavior of noble gases?
They are zero valent and exist as monoatomic
This is due to their stable electronic configuration and lack of tendency to gain or lose electrons.
What oxidation states occur in oxides and oxoacids of Cl and Br?
+4 and +6
Why can’t fluorine expand its octet?
It has no d-orbitals in its valence shell and is highly electronegative, exhibiting mostly –1 oxidation state.
What is the electronic configuration of Group 18 elements?
ns2np6
Why are noble gases considered zero valent?
They have no tendency to gain or lose electrons.
What unique property allows xenon to exhibit higher oxidation states?
It has an expandable d-orbital.
Provide examples of xenon compounds in higher oxidation states.
- XeF2 (+2)
- XeF4 (+4)
- XeF6 (+6)
- XeO3 (+6)
- XeOF4 (+6)
What type of hydrides do Group 16 elements form with hydrogen?
H2E where E = O, S, Se, Te, Po
What is the acidic character of hydrides in Group 16?
Weakly acidic
As you move from H2O to H2Te, what happens to the acidic character and thermal stability?
Acidic character increases and thermal stability decreases.
Fill in the blank: The bond dissociation enthalpy of H−E bond ______ from H2O to H2Te.
decreases
Arrange the following hydrides in order of reducing property: H2S, H2Se, H2Te.
H2S < H2Se < H2Te
What is the order of acidic strength of hydrogen halides?
HF < HCl < HBr < HI
True or False: The thermal stability of hydrogen halides decreases in the order HF > HCl > HBr > HI.
True
What type of oxides do Group 16 elements form?
EO2 and EO3 where E = S, Se, Te, Po
What are the properties of SO2 and SeO2?
- SO2 is a gas and acidic in nature.
- SeO2 is solid and also acidic.
What do EO3 type oxides dissolve in water to form?
Acids
What is the chemical equation for the formation of sulphurous acid from SO2?
SO2 + H2O → H2SO3
What are the two thermally stable oxides formed by fluorine?
OF2 and O2F2
What is the stability trend of halogen oxides?
Higher oxides are more stable than lower ones.
What type of compounds do halogens form with themselves?
Interhalogen compounds
What is the chemical reaction for the formation of metal halides by halogens?
2Na(s) + Cl2(l) → 2NaCl(s)
What is the trend of ionic character in metal halides?
MF > MCl > MBr > MI
What are the two allotropes of oxygen?
O2 and O3 (ozone)
What are the two important allotropes of sulfur?
Rhombic sulfur (α-sulfur) and Monoclinic sulfur (β-sulfur)
What is the method of preparation for rhombic sulfur?
Evaporation of roll sulfur in CS2
What is the acidic strength trend of halogen oxoacids?
Increases with increasing oxidation state of halogen.
What are the stable oxoacids of halogens?
- Hypofluorous acid (HOF)
- Perchloric acid (HClO4)
- Iodic acid (HIO3)
- Metaperiodic acid (H2IO6)
What are the laboratory methods for preparing dioxygen?
- Heating oxygen-containing salts
- Thermal decomposition of metal oxides
- Decomposition of hydrogen peroxide
What are the physical properties of dioxygen?
- Colourless and odourless gas
- Sparingly soluble in water
- Liquefies at 90 K
- Freezes at 55 K
What is the primary use of dioxygen?
Respiration to sustain animal and aquatic life
What is the reaction for the formation of sulfur trioxide from sulfur dioxide and oxygen?
2SO2 + O2 –⎯⎯→ 2SO3
What is dioxygen’s role in respiration?
It sustains animal and aquatic life.
List three uses of oxygen.
- Manufacturing of steel
- Oxyacetylene flame for welding and cutting
- Oxygen cylinders in hospitals
What is a binary compound of oxygen with another element called?
Oxide
What type of oxide dissolves in water to give an acid?
Acidic oxide
Provide an example of an acidic oxide.
SO2
What characterizes a basic oxide?
It dissolves in water to give a base or reacts with an acid to give salt.
Give an example of a basic oxide.
Na2O
What is an amphoteric oxide?
An oxide that reacts with both an acid and a base.
Provide an example of an amphoteric oxide.
Al2O3
What are neutral oxides?
Oxides that are neither acidic nor basic.
Provide an example of a neutral oxide.
CO
What is ozone (O3)?
An allotrope of oxygen
How is ozone formed in the upper atmosphere?
Oxygen absorbs UV light and changes to atomic oxygen, which combines with molecular oxygen.
What is the protective function of the ozone layer?
It protects the earth’s surface from harmful UV radiations.
What process is used to prepare ozone in the laboratory?
Passing silent electric discharge through pure and dry oxygen.
What is the physical state of pure ozone?
- Pale-blue gas
- Dark blue liquid
- Violet-black solid
True or False: Ozone is a powerful oxidizing agent.
True
What happens when ozone oxidizes lead sulfide?
It forms lead sulfate.
What is ozone depletion?
Thinning of the ozone layer in the upper atmosphere.
List two causes of ozone depletion.
- NO from exhaust systems
- Chloro-fluoro-carbons (freons)
What are some uses of ozone?
- Air purification
- Sterilizing drinking water
- Bleaching delicate fabrics
What is the preparation reaction for sulfur dioxide from sulfur?
S(s) + O2(g) → SO2(g)
What is the physical property of sulfur dioxide?
Colorless gas with a pungent smell.
Sulfuric acid is produced by which process?
Contact process
What is the first step in the manufacture of sulfuric acid?
Burning sulfur to produce sulfur dioxide.
What is the density of sulfuric acid at 298 K?
1.84 g/cm3
What characterizes chlorine gas?
Greenish-yellow color and pungent odor.
What is the Deacon’s process used for?
Manufacturing chlorine.
What happens when chlorine reacts with metals?
It forms chlorides.
What is the reaction of chlorine with hydrogen?
H2 + Cl2 → 2HCl
What is the boiling point of chlorine?
293 K
What is the chemical reaction for the preparation of chlorine using manganese dioxide?
MnO2 + 4HCl → MnCl2 + Cl2 + 2H2O
What is the reaction of chlorine with hydrogen?
H2 + Cl2 → 2HCl
Chlorine has a great affinity for hydrogen, forming hydrochloric acid.