Topic 11 Group 14

The following are high-level thinking skills (KBAT) questions designed based on the learning outcomes provided:

– What is melting point and boiling point?

The boiling point is the temperature at which a material changes from a liquid to a gas (boils) while the melting point is the temperature at which a material changes from a solid to a liquid (melts). Keep in mind that a material’s melting point is the same as its freezing point.

 

– When down to group 14, what happens to their melting point and why is it so?

Decreases. When down to group 14, the size of atom is increasing. The attractive force between the atom will decrease.

 

– Why are melting points different?

Different solids have different melting points depending on the strength of bonding between the particles and the mass of the particles. Essentially, the heavier the particles in the solid, and the stronger the bonding, the higher the melting point.

 

– What factors affect melting point?

1. Molecular composition

2. force of attraction (The stronger the forces that act between molecules of a substance (intermolecular forces), the higher the melting point tends to be) and

3. the presence of impurities can all affect the melting point of substances.

 

– Which element has the highest melting point in the periodic table?

Carbon. 

 

– Which element has the lowest melting point in the periodic table?

Helium. 

 

– Which element has the lowest melting point in the group 14?

Stanum.

 

– What is Carbon’s melting point ans boiling point?

Carbon. 

melting point = 3,550 °C (6,420 °F). 

boiling point = 4,827 °C (8,721 °F)

 

– Which metal has the highest melting point in the periodic table?

tungsten. Of all metals in pure form, tungsten has the highest melting point (3,422 °C, 6,192 °F), lowest vapor pressure (at temperatures above 1,650 °C, 3,000 °F), and the highest tensile strength.

 

https://www.angstromsciences.com/melting-points-of-elements-reference 

 

– Which metal has the lowest melting point in the periodic table?

mercury. Among the metallic elements, only mercury has a lower melting point (−38.9 °C, or −38.02 °F) than cesium (28.44 °C).

 

– What is the trend for melting point in terms of across period and down to the group in the periodic table?

Across period: The melting point of period three elements increases from sodium to silicon and decreases from silicon to argon. In general, melting point increases across a period up to group 14, then decreases from group 14 to group 18.

 Down to the group: The melting point of group 14 when down to group is decreases. From carbon to stanum is decrease and slightly increase from Sn to plumbum.

 

– What liquids don’t freeze?

Liquid helium. It only condenses to a liquid at about 4 K (-269.15°C). At standard pressures, helium remains a liquid all the way down to absolute zero (0 K). It can be made to solidify only under great pressures (25+ atmospheres) at very close to 0 K.

 

– How does the size of the atom change with the melting point?

When down to the group, the bp and mp will decrease. Boiling and melting point depends on the amount of force. When the protons are more, the force of attraction will be less, hence less heat energy will be required to overcome the force of attraction. Hence low melting and boiling point. And the vice versa will happen in smaller atoms or molecules.

 

– What metal is hardest to melt?

Tungsten

Tungsten (1960–2450 MPa) Tungsten is one of the hardest metals you will find in nature. Also known as Wolfram, the rare chemical element exhibits a high density (19.25 g/cm3) as well as a high melting point (3422 °C/ ​6192 °F).

 

– What is the strongest metal in the world?

tungsten

In terms of tensile strength, tungsten is the strongest out of any natural metal (142,000 psi). But in terms of impact strength, tungsten is weak — it’s a brittle metal that’s known to shatter on impact. Titanium, on the other hand, has a tensile strength of 63,000 psi.

 

– How to explain melting point in group 1?

Generally the melting point of the alkali metals decreases down the group. This is because as the ions get larger the distance between the bonding electrons and the positive nucleus gets larger and reduces the overall attraction between the two. For similar reasons the electronegativity decreases.

 

– How to explain melting point in group 2?

Group 2 elements are held together by metallic bonds. The melting points decrease down the group because the metallic bonds are weaker for the larger elements.

 

– How to explain melting point in group 14?

Group 14 (carbon family) elements have much higher melting points and boiling points than the group 13 elements. Melting and boiling points in the carbon family tend to decrease moving down the group, mainly because atomic forces within the larger molecules are not as strong.

 

– What is the type of bond that is related to group 14 elements’ melting points?

Group 14 consists of carbon, silicon, germanium, tin, and lead. Carbon is a non-metal, silicon and germanium are metalloids, and tin and lead are metals. With 4 valence shell electrons, elements of the carbon family tend to form covalent compounds. With increasing mass and atomic radius these elements become increasingly metallic and have lower melting and boiling points.

 

– Why melting point increases down the group in non metal?

Melting and Boiling Points (increases down the group). The melting and boiling points increase down the group because of the van der Waals forces. The size of the molecules increases down the group. This increase in size means an increase in the strength of the van der Waals forces.

 

– Why does the melting point of Group 2 decrease?

The melting points decrease down the group because the metallic bonds are weaker for the larger elements. The atoms in a metal are held together by the attraction between the nuclei and the delocalized electrons.

 

– Why does the melting point of Group 14 decrease?

All the elements of group14 possess diamond-type lattice structure which is highly stable in nature. The process of melting results in the breakage of these highly stable lattice structures. Down the group, the melting point decreases as the M-M bonds are reduced as the size of the atoms increases.

 

Covalent solids are a class of extended-lattice compounds in which each atom is covalently bonded to its nearest neighbors. This means that the entire crystal is, in effect, one giant molecule. The extraordinarily strong binding forces that join all adjacent atoms account for the extreme hardness of these solids.

 

– What is the difference in characteristics of giant covalent and giant metallic structure?

Covalent giant structures: are very hard, because the covalent bonds are very strong. have very high melting temperatures, because huge amounts of energy are needed to break covalent bonds. Metals are giant structures with metal ions arranged in a regular, repeating lattice with layers of metal ions. Giant metallic structures are held together by strong metallic bonds. These are strong electrostatic attractions between the positive metal ions and the surrounding negative delocalised electrons. Giant covalent structures are made up of many covalent bonds between atoms. They have high melting points because it takes a lot of energy to break the strong covalent bonds between the atoms. They cannot conduct electricity because they have no overall charge.

 

– Why do giant metallic structures have high melting points?

They are good conductors of thermal energy because their delocalised electrons transfer energy. They have high melting points and boiling points , because the metallic bonding in the giant structure of a metal is very strong – large amounts of energy are needed to overcome the metallic bonds in melting and boiling.

 

– Do giant metallic structures conduct electricity?

Metals have giant structures of atoms with delocalised electrons. This explains their high melting and boiling points and why they conduct electricity.

 

– What compounds can form giant structures?

An example – silica

Silica is the main compound found in sand. It is an example of a giant covalent substance. It contains many silicon and oxygen atoms. These are joined together by covalent bonds in a regular arrangement, forming a giant covalent network or lattice structure.

 

– What are the key differences between simple covalent molecules and giant covalent structures?

As a result, simple covalent substances generally have low melting/boiling points. Giant covalent substances, such as diamond, contain many strong covalent bonds in a 3D lattice structure. Between each carbon atom in diamond, there are 4 strong covalent bonds.

 

– Do covalent bonds form lattices?

Actually, giant covalent lattices do exist. They do have covalent bonds ie strong electrostatic forces of attraction between positively charged nucleus and negatively charged shared pair of valence electrons. So all the 3 types of chemical bonding – ionic, metallic and covalent form lattices.

 

– What is a covalent lattice?

A covalent lattice (also called a covalent network) is a continuous network of atoms that are joined together through covalent bonds. There are some compounds that form covalent lattices, but in this lesson we will focus only on elements that form covalent lattices.

 

Covalent Bonds

A covalent bond, as the name suggests, is a crystal structure in which the electrons do not leave their orbits. Electrons, instead, are shared between two atoms. … The bound atoms further share another electron from the atoms next to them and so on.

 

– What elements have a covalent molecular structure?

A covalent network structure consists of a giant 3-dimensional lattice of covalently bonded atoms. Boron, carbon and silicon are all examples of covalent network elements. Diamond and graphite, two forms of carbon and compounds like silicon dioxide and silicon carbide are all covalent networks.

 

– What is the relation between carbon can form 4 covalent bonds each atom with melting point?

Carbon contains four electrons in its outer shell. Therefore, it can form four covalent bonds with other atoms or molecules. The simplest organic carbon molecule is methane (CH4), in which four hydrogen atoms bind to a carbon atom (Figure 1). However, structures that are more complex are made using carbon.

 

– Carbon can form 4 covalent bonds each atom, same goes to silicon, then why does silicon have a lower melting point? Why does carbon have a higher melting point than silicon?

Silicon like Carbon has covalent bonding as it is group 4 like Carbon. … Also The Bond length between CarbonCarbon atoms is lesser than that of Silicon making it harder to break the bonds. Hence Carbon has much higher melting point than that of Silicon.

– Why do giant covalent structures have high melting?
Substances with giant covalent structures are solids at room temperature. They have very high melting points and boiling points . This is because large amounts of energy are needed to overcome their strong covalent bonds to make them melt or boil.

– What is inert pair effect explain with example?

The inert pair effect is defined as the tendency of electrons in the outermost atomic s orbital to remain unionized in compounds of post-transition metals [1]. For simplicity, let’s summarize it as the tendency of heavier atoms to form ions with a difference in charge of two.

– What is the reason for inert pair effect?

Inert pair effect is mostly shown by the 15-17th group elements. That is, the oxidation state reduces by 2 for elements below (As, Sb), which is more stable than the other oxidation states. The reason for this is the inertness of the inner s electrons due to poor shielding.

– Why does inert pair effect increase down the group?

Since inert pair effect refers to the tendency of outermost electrons to remain unionized, the stability of the oxidation state of the elements down a particular group increases.

…….

11.0 Group 14

11.1 Physical properties of Group 14 elements

1. Explain the reason why trends in physical properties:

a. melting points and
b. electrical conductivity

of Group 14 elements:

melting point:

C: 3700°C,
Si: 1410°C,
Ge: 936°C,
Sn: 232°C,
Pb: 328°C.

electrical conductivity:

C: diamond (x), graphite (/),
Si: semiconductor,
Ge: semiconductor,
Sn: good conductor,
Pb: good conductor,

11.2 Tetrachlorides and oxides of Group 14 elements

1. What determines the molecular geometry of a molecule?

2. How do bonding affect molecular shapes of the tetrachlorides of group 14 elements?

3. Explain the volatility, thermal stability and hydrolysis of tetrachlorides in terms of structure and bonding?

4. What is the inert pair effect in simple language?

5. What is the reason for the inert pair effect?

6. Is inert pair effect and shielding effect same?

7. Explain the bonding, acid-base nature and the thermal stability of the oxides of oxidation states +2 and +4?

11.3 Relative stability of +2 and +4 oxidation states of Group 14 elements

1. Why is it Pb2+ more stable than Pb4+?

2. Explain the relative stability of +2 and +4 oxidation states of the elements in their oxides, chlorides and aqueous cations.

11.4 Silicon, silicone and silicates

1. Explain the uses of silicon as a semiconductor and silicone as a fluid, elastomer and resin;

2. Describe the uses of silicates as basic materials for cement, glass, ceramics and zeolites.

11.5 Tin alloys

1. Describe the uses of tin in solder and pewter.

11 Group 14

11.1 Physical properties of Group 14 elements

Candidates should be able to:

(a) explain the trends in physical properties (melting points and electrical conductivity) of Group 14 elements: C, Si, Ge, Sn, Pb.

11.2 Tetrachlorides and oxides of Group 14 elements

Candidates should be able to:

(a) explain the bonding and molecular shapes of the tetrachlorides of group 14 elements;

(b) explain the volatility, thermal stability and hydrolysis of tetrachlorides in terms of structure and bonding;

(c) explain the bonding, acid-base nature and the thermal stability of the oxides of oxidation states +2 and +4.

11.3 Relative stability of +2 and +4 oxidation states of Group 14 elements

Candidates should be able to:

(a) explain the relative stability of +2 and +4 oxidation states of the elements in their oxides, chlorides and aqueous cations.

11.4 Silicon, silicone and silicates

Candidates should be able to:

(a) describe the structures of silicone and silicates (pyroxenes and amphiboles), sheets (mica) and framework structure (quartz) (general formulae are not required);

(b) explain the uses of silicon as a semiconductor and silicone as a fluid, elastomer and resin;

(c) describe the uses of silicates as basic materials for cement, glass, ceramics and zeolites.

11.5 Tin alloys

Candidates should be able to:

(a) describe the uses of tin in solder and pewter.

11 Group 14

11.1 Physical properties of Group 14 elements

Candidates should be able to:

(a) explain the trends in physical properties (melting points and electrical conductivity) of Group 14 elements: C, Si, Ge, Sn, Pb.

11.2 Tetrachlorides and oxides of Group 14 elements

Candidates should be able to:

(a) explain the bonding and molecular shapes of the tetrachlorides of group 14 elements;

(b) explain the volatility, thermal stability and hydrolysis of tetrachlorides in terms of structure and bonding;

(c) explain the bonding, acid-base nature and the thermal stability of the oxides of oxidation states +2 and +4.

11.3 Relative stability of +2 and +4 oxidation states of Group 14 elements

Candidates should be able to:

(a) explain the relative stability of +2 and +4 oxidation states of the elements in their oxides, chlorides and aqueous cations.

11.4 Silicon, silicone and silicates

Candidates should be able to:

(a) describe the structures of silicone and silicates (pyroxenes and amphiboles), sheets (mica) and framework structure (quartz) (general formulae are not required);

(b) explain the uses of silicon as a semiconductor and silicone as a fluid, elastomer and resin;

(c) describe the uses of silicates as basic materials for cement, glass, ceramics and zeolites.

11.5 Tin alloys

Candidates should be able to:

(a) describe the uses of tin in solder and pewter.

Add Comment