KEY NOTES – iconic compound- Class 10 – Science -Chemistry -Chapter 3 – Metals and Non-metals

KEY NOTES –  iconic compound- Class 10 – Science -Chemistry -Chapter 3 – Metals and Non-metals  

Ionic Compounds:

1. Definition:

Ionic compounds are chemical compounds composed of positively charged ions (cations) and negatively charged ions (anions) held together by electrostatic forces, primarily ionic bonds.

2. Formation:

Ionic compounds typically form between metals and non-metals through the transfer of electrons.

3. Properties:

High Melting and Boiling Points:

Ionic compounds have high melting and boiling points due to the strong electrostatic forces holding ions together in a crystal lattice.

Solubility in Water:

Many ionic compounds are soluble in water, as water molecules surround and stabilize individual ions, facilitating their separation.

Conductivity:

In the molten or dissolved state, ionic compounds can conduct electricity, as ions are free to move and carry an electric current.

Color:

Many ionic compounds exhibit characteristic colors due to the presence of specific metal ions.

Reactivity Series :

The reactivity series is a list that ranks metals in order of their reactivity, based on how readily they form positive ions in chemical reactions.

The arrangement of metals in order of decreasing reactivities is called reactivity series or activity series of metals

Order of Reactivity:

Metals higher in the reactivity series are more reactive and tend to displace metals lower in the series from their compounds in single displacement reactions.

Common Reactivity Series:

Common elements in the reactivity series include potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), aluminium (Al), zinc (Zn), iron (Fe), copper (Cu), silver (Ag), and gold (Au).

Observations:

A more reactive metal can displace a less reactive metal from its compound during a reaction.

For example, zinc can displace copper from copper sulphate:

Zn + CuSO4 àZnSO4  + Cu

Usefulness:

The reactivity series helps predict the outcome of displacement reactions and understand the relative tendencies of metals to form positive ions.

Metals Below Hydrogen:

Metals below hydrogen in the series (e.g., copper, silver, gold) do not react with dilute acids.

Application in Extraction:

The series is also useful in understanding the feasibility of extracting metals from their ores, as metals higher in the series are often easier to extract.

Covalent Bond:

A covalent bond is a type of chemical bond formed between two atoms when they share one or more pairs of electrons. This sharing of electrons allows each participating atom to achieve a more stable electron configuration, often resembling that of a noble gas. Covalent bonds commonly occur between non-metal atoms.

In a covalent bond:

Electrons are shared between the participating atoms.

The shared electrons occupy the overlapping orbitals of both atoms.

The bond is directional, with the shared electrons spending more time in the region between the two nuclei.

 Corrosion:

Metals can corrode when exposed to air and moisture.

Protective measures include painting, coating with zinc (galvanization), and using alloys resistant to corrosion.