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Chemistry > The Particulate Nature of Matter > Flashcards

The Particulate Nature of Matter Flashcards

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1
Q

Define isotopes

A

Isotopes are atoms of the same element with the same no. of protons but different no. of neutrons

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2
Q

Explain the stability of electrons based on the position of its electron shells

A

• The closer the electron shell is to the nucleus of an atom, the electrons will have a lower energy level and hence be most stable
• The further the electron shell is from the nucleus of an atom, the electrons will have a higher energy level and hence be less stable

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3
Q

Uses of isotopes

A

• Medical field:
- detection of tumors
- treatment of thyroid disorder
• Safety and Security field:
- detect explosives
- used in smoke detectors
• Archaeology:
- Estimate age of things containing carbon
• Geology:
- Estimate age of rocks

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4
Q

Trend across the period

A

• Increasing atomic number
• more no. of electrons
• elements change from metallic to non-metallic

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5
Q

Trend down the Group

A

• Increasing no. of electrons shells
• Elements have larger atomic radius
• Weaker forces of attraction between nucleus of atom and valence electrons

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6
Q

Why do elements in the same group have similar chemical properties?

A

They have the same no. of valence electrons

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7
Q

Relative charge of Proton

A

+1

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8
Q

Relative charge of Neutron

A

0

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9
Q

Relative charge of Electron

A

-1

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10
Q

Relative mass of Proton

A

1

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11
Q

Relative mass of Neutron

A

1

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12
Q

Relative mass of Electron

A

1/1840

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13
Q

Definition of an ionic compound

A

An ionic compound is the strong electrostatic force of attraction between oppositely charged ions in a compound

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14
Q

Why does sodium chloride have very hard crystals?

A

Sodium chloride is an ionic compound held by strong ionic bonds between sodium cations and chloride anions in a giant ionic crystal lattice structure. This is due to strong electrostatic forces of attraction between oppositely charged ions resulting in very hard crystals.

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15
Q

Why do sodium chloride crystals have a regular shape?

A

The sodium cations and chloride anions are held together in fixed positions in the giant ionic crystal lattice structure.

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16
Q

Why are ionic compounds non-volatile?

A

An ionic compound has a giant ionic crystal lattice structure held by strong ionic bonds between oppositely charged ions. Hence an ionic compound cannot be easily evaporated resulting in an ionic compound to remain as a solid at room temp. and pressure without producing any smell.

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17
Q

Why do ionic compounds have high melting/boiling points?

A

An ionic compound has a giant ionic crystal lattice structure held by strong ionic bonds between oppositely charged ions. Each cation and anion are held together by strong electrostatic forces of attraction between oppositely charged ions. Hence a large amount of heat energy is required to overcome these strong forces of attraction between oppositely charged ions resulting in the ionic compounds to have a high melting/boiling point.

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18
Q

Why does MgO have a higher melting/boiling point than NaCl?

A

The cations in MgO have a +2 positive charge and the anions have a -2 negative charge. The ionic bonds in MgO are stronger than the ionic bonds in NaCl due to the stronger electrostatic forces of attraction between the oppositely doubly charged ions in the giant ionic crystal lattice structure of MgO. Therefore a larger amount of heat energy is required to overcome the stronger electrostatic forces of attraction between oppositely doubly charged ions in MgO resulting in MgO having a higher melting/boiling point.

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19
Q

Why are most ionic compounds soluble in water?

A

There is an attraction between the ions in the ionic compound and the water molecules. Hence the ions separate and go into the solution.

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20
Q

Why are most ionic compounds insoluble in organic solvents?

A

There is no attraction between the ions of the ionic compound and the molecules of the organic solvent. Hence the ions will not separate and go into the solution.

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21
Q

Why don’t ionic compounds conduct electricity in solid state?

A

In solid state, ions in an ionic compound are immobile and cannot move due to strong electrostatic forces of attraction between oppositely charged ions in the giant ionic crystal lattice structure. Hence the ions cannot carry the negative electric charge during conduction. Therefore ionic compounds cannot conduct electricity in solid state.

22
Q

Why can ionic compounds conduct electricity in molten state?

A

In molten state, ions in an ionic compound are mobile and hence can move and carry the negative electric charge during conduction

23
Q

Why can aqueous ionic compounds conduct electricity?

A

In aqueous state, ionic compounds dissolve in water to form their respective cations and anions. These mobile ions can move and carry the negative electric charge during conduction. Therefore, aqueous ionic compounds can conduct electricity.

24
Q

How does size of an ion affect strength of an ionic bond?

A

A larger ion makes a weaker ionic bond due to the greater the distance between electrons and the nucleus of the oppositely charged ion.

25
Q

How does charge of an ion affect strength of an ionic bond?

A

The higher the charge of an ion, the greater the electrostatic forces of attraction between oppositely charged ions resulting in a stronger ionic bond.

26
Q

Uses of simple molecules

A

Simple molecules are volatile and evaporate easily to produce a smell hence small amounts of volatile covalent compounds are used in perfumes and flavourings to produce a pleasant smell.

27
Q

Define covalent bonding

A

Covalent bonding is the result when atoms are joined together by the sharing of electrons, forming molecules.

28
Q

Why do simple molecules exist as liquids/gases at room temp. ?

A

Simple molecules are held by weak Van Der Waals’ forces, hence the molecules are not held as tightly as particles in solid state.

29
Q

Why do simple molecules have low m.p./b.p. ?

A

Simple molecules have weak intermolecular forces of attraction between molecules. A small amount of heat energy is required to overcome the weak intermolecular forces of attraction. Hence simple molecules have low m.p./b.p.

30
Q

Solubility of simple molecules

A

Most simple molecules are insoluble in water and soluble in organic solvents

31
Q

Electrical conductivity of simple molecules

A

Simple molecules cannot conduct electricity as they do not have free and mobile electrons that can move to carry the negative electric charge during conduction

32
Q

M.p/B.p of giant molecules

A

Giant molecules have a large no. of carbon atoms which are held together by strong covalent bonds between atoms. Hence a large amount of heat energy is required to overcome these strong covalent bonds

33
Q

Solubility of giant molecules

A

Giant molecules are insoluble in both water and organic solvents. In giant molecules, all atoms are held together by strong covalent bonds hence any forces of attraction between the the giant molecules and solvent molecules are not enough to overcome the stronger covalent bonds

34
Q

Electrical conductivity of giant molecules

A

Giant molecules do not conduct electricity. In giant molecules, all outer electrons of atoms are used to form covalent bonds hence there are no free and mobile electrons that can move to carry the negative electric charge during conduction headphones

35
Q

What are allotropes

A

Allotropes are different forms of the same element

36
Q

Why does diamond have a high m.p/b.p ?

A

Diamond is a giant molecule made up of a large network of many carbon atoms. Each carbon atom is bonded to 4 other carbon atoms by strong covalent bonds in a giant rigid tetrahedral structure. Hence a large amount of heat energy is required to overcome the many strong covalent bonds between each carbon atom in the structure.

37
Q

Why does diamond not conduct electricity?

A

Diamond is a giant molecule made up of a large network of many carbon atoms. Each carbon atom is bonded to 4 other carbon atoms by strong covalent bonds in a giant rigid tetrahedral structure. All 4 valence electrons of carbon atoms are used for covalent bonding hence there are no free and mobile electrons that can move to carry the electric charge during conduction.

38
Q

Why is diamond very hard?

A

Diamond is a giant molecule made up of a large network of many carbon atoms. Each carbon atom is bonded to 4 other carbon atoms by strong covalent bonds in a giant rigid tetrahedral structure. The presence of strong covalent bonds between each carbon atom in the structure makes diamond very stable and hard as a lot of force is required to overcome these strong covalent bonds.

39
Q

Uses of diamonds

A

• Tips of drills for drilling
• Grinding
• Polishing very hard surfaces

40
Q

Why does graphite have a high m.p/b.p ?

A

Graphite is a giant molecule made up of a giant network of planar hexagonal ring layers. Within each layer, each carbon atom is bonded to 3 other carbon atoms by strong covalent bonds. Hence a lot of heat energy is required to overcome these strong covalent bonds.

41
Q

Why can graphite conduct electricity ?

A

Graphite is made up of a giant network of planar hexagonal ring layers. Each carbon atom is bonded to 3 other carbon atoms by strong covalent bonds. In graphite, each carbon atom has 4 valence electrons but only 3 valence electrons are used to form strong covalent bonds with 3 other carbon atoms in a giant network of planar hexagonal ring layers. There will be one free and mobile valence electron per carbon atom to move and carry the negative electric charge during conduction

42
Q

Why does graphite act as a lubricant?

A

Graphite is made up of a giant network of planar hexagonal ring layers. Each carbon atoms is bonded to 3 other carbon atoms by strong covalent bonds. Between each hexagonal ring layer of carbon atoms, there exists weak intermolecular forces of attraction holding them together. Lesser amount of energy and force is required to overcome these weak intermolecular forces of attraction. Hence, the hexagonal ring layers can slide over one another easily, leading it to have a soft and slippery nature.

43
Q

Uses of graphite

A

• dry lubricant ( soft )

• brushes for electric motors ( good conductor of electricity )

• to make inert electrodes for electrolysis ( good conductor of electricity, will not react with electrolyte )

• baked with clay to make pencil lead ( soft , carbon layers flake off and stick to paper when we write )

44
Q

Why does silicon dioxide have a high m.p/b.p ?

A

Silicon dioxide is a giant molecule made up of a large network of many silicon and oxygen atoms. Each silicon atom is bonded to 4 other oxygen atoms by strong covalent bonds in a giant rigid tetrahedral structure. Hence, a large amount of heat energy is required to overcome the many strong covalent bonds between each atom

45
Q

Why does silicon dioxide not conduct electricity?

A

Silicon dioxide does not have free and mobile electrons that can move to carry the negative electric charge during conduction

46
Q

Define metallic bonding

A

Metallic bonding is the strong electrostatic forces of attraction between the surrounding ‘sea of delocalized mobile negatively charged valence electrons’ and positively charged metal ions

47
Q

Electrical conductivity of metals

A

Metals are good conductors of electricity because there exists a ‘sea of delocalized mobile negatively charged valence electrons ‘ available within the giant metal lattice structure that can move to carry the negative electric charge during conduction

48
Q

Heat conductivity of metals

A

Metals are good conductors of heat because heat is easily transferred by the ‘sea of delocalized mobile negatively charged valence electrons’ in the giant metal lattice structure. The electrons can move freely to conduct transfer heat energy

49
Q

Density of metals

A

Metals have high density as the atoms in the giant metal lattice structure are packed tightly in an orderly and rigid layer arrangement

50
Q

M.p/B.p of metals

A

Metallic bonding is the strong electrostatic forces of attraction between the surrounding ‘sea of delocalized mobile negatively charged valence electrons’ and positively charged metal ions. Hence, a large amount of heat is required to overcome the strong electrostatic forces of attraction. Therefore, metals have high m.p/b.p

51
Q

Why are metals malleable and ductile?

A

When a force is applied to a metal, layers of atoms slide over one another through the ‘sea of delocalized mobile negatively charged valence electrons’ without disrupting the metal lattice as there is metallic bonding between the sea of electrons and positively charged metal ions. Hence, metals are strong but flexible as they are malleable and ductile

52
Q

Physical properties of metals

A

• Shiny grey solids ( except mercury )
• produces a deep, resonant sound

Chemistry (7 decks)

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