Electrovalency in Chemistry

Questions and Answers

What is the positive electrovalency of sodium (Na)?

+1 (correct)

Which of the following elements has a negative electrovalency of -2?

Sodium (Na)

Nitrogen (N)

Oxygen (O) (correct)

Chlorine (Cl)

What type of bond is formed by the transfer of electrons?

Covalent bond

Metallic bond

Coordinate bond

Ionic bond (correct)

Which characteristic is NOT typical of ionic compounds?

Low melting point Signup and view all the answers

What is the covalency obtained by sharing four electrons called?

Double covalency Signup and view all the answers

In a covalent bond, what do atoms do?

Share electrons Signup and view all the answers

Which of the following is an example of an ionic compound?

NaCl Signup and view all the answers

How many electrons does nitrogen gain to form N3-?

3 Signup and view all the answers

What is the primary characteristic that defines the atomic number of an element?

The number of protons in the nucleus Signup and view all the answers

Why does an electron not fall into the nucleus of an atom?

Electric forces are balanced by centrifugal forces. Signup and view all the answers

Which of the following statements is true regarding the mass of subatomic particles?

Electrons have a negligible mass compared to protons and neutrons. Signup and view all the answers

What is the charge of a neutron within an atom?

Neutral Signup and view all the answers

Which of the following best describes a molecule?

The smallest particle of a substance made of two or more atoms Signup and view all the answers

What is the significance of the balance between protons and electrons in an atom?

It causes the atom to be electrically neutral. Signup and view all the answers

What does the atomic number of an element indicate?

The number of protons and electrons in an atom Signup and view all the answers

Who discovered the electron?

J.J. Thomson Signup and view all the answers

What is the atomic mass number defined as?

The sum of the number of protons and neutrons in the nucleus Signup and view all the answers

If an atom has a mass number of 24 and an atomic number of 13, how many neutrons does it have?

11 Signup and view all the answers

What role do neutrons play in the nucleus of an atom?

They increase the atomic mass. Signup and view all the answers

Which of the following configurations correctly represents the electronic configuration of Sodium (Na)?

(2, 8, 1) Signup and view all the answers

Which orbital can hold a maximum of 10 electrons?

d orbital Signup and view all the answers

Which of the following does NOT determine the position of an element in the periodic table?

Atomic mass number Signup and view all the answers

In the formula for calculating the maximum number of electrons in different orbits, what does the variable 'n' represent?

The shell number or energy level Signup and view all the answers

How many electrons can be found in an s orbital?

2 Signup and view all the answers

What characteristic is true for covalent compounds?

They are insoluble in polar solvents. Signup and view all the answers

Which of the following describes the coordinate bond?

It involves the donation of a lone pair from one atom to another. Signup and view all the answers

Which statement about hydrogen bonding is correct?

Compounds with hydrogen bonding typically have high boiling points. Signup and view all the answers

What defines intermolecular hydrogen bonding?

Hydrogen bonding between different molecules. Signup and view all the answers

Which of the following statements is true regarding coordinate bonds and covalent compounds?

Coordinate bonds usually have higher melting points than covalent bonds. Signup and view all the answers

Which compound would most likely display intramolecular hydrogen bonding?

Amino acids with functional groups Signup and view all the answers

What is a property of hydrogen bonds compared to other types of bonds?

Hydrogen bonds are weaker than covalent and ionic bonds. Signup and view all the answers

In which situation would a compound most likely not exhibit hydrogen bonding?

When there are no hydrogen atoms present. Signup and view all the answers

What characterizes amorphous solids compared to crystalline solids?

Their particles are randomly arranged. Signup and view all the answers

Which of the following is a correct description of a unit cell in a simple cubic lattice?

Atoms are located at the corners of the cube. Signup and view all the answers

What is the coordination number for atoms in a simple cubic structure?

6 Signup and view all the answers

Which type of crystal lattice has atoms at each corner and one atom in the center?

Body centered cubic Signup and view all the answers

Which type of solid is described as having high viscosities and behaving like supercooled liquids?

Amorphous solids Signup and view all the answers

What can be said about the bond angles and side lengths of a simple cubic unit cell?

All sides are equal and bond angles are 90O Signup and view all the answers

Which of the following best describes a crystal lattice?

A highly ordered three-dimensional structure Signup and view all the answers

Which of the following materials is an example of an amorphous solid?

Rubber Signup and view all the answers

Study Notes

Electrovalency

Positive Electrovalency: Represents the number of electrons lost by an atom.
Sodium (Na) loses 1 electron to form Na+, with a configuration change from (2,8,1) to (2,8).
Magnesium (Mg) loses 2 electrons to become Mg2+, changing from (2,8,2) to (2,8).
Calcium (Ca) also loses 2 electrons, forming Ca2+, altering from (2,8,8,2) to (2,8,8).
Negative Electrovalency: Indicates the number of electrons gained to complete the outer shell.
Chlorine (Cl) gains 1 electron to form Cl-, transitioning from (2,8,7) to (2,8,8).
Oxygen (O) gains 2 electrons to form O2-, with a shift from (2,6) to (2,8).
Nitrogen (N) gains 3 electrons to form N3-, changing from (2,5) to (2,8).

Chemical Bonds

A chemical bond is the attractive force between atoms in a molecule.
Types of bonds include:
- Ionic bond (electrovalent bond)
- Covalent bond
- Coordinate (dative) bond
- Hydrogen bond
- Metallic bond
Ionic Bond: Formed by the transfer of electrons. Examples are NaCl, MgO, and CaO.
Characteristics of Ionic Compounds:
- Soluble in water
- Conduct electricity
- High melting and boiling points
- Non-directional

Covalency

Describes how many electrons are shared to fill the outer shell.
Single Covalency: Sharing one pair of electrons, e.g., H2, Cl2.
Double Covalency: Sharing two pairs, e.g., O2.
Triple Covalency: Sharing three pairs, e.g., N2.

Structure of an Atom

An atom is the smallest unit of an element, consisting of protons, neutrons, and electrons.
Atoms are electrically neutral due to equal numbers of protons and electrons.
Fundamental particles:
- Proton (P): +1 charge, located in the nucleus, discovered by Rutherford.
- Neutron (n): Neutral, also in the nucleus, discovered by Chadwick.
- Electron (e-): -1 charge, located outside the nucleus, discovered by Thomson.
Atomic structure influences physical and chemical properties.

Atomic Number and Mass Number

Atomic Number (Z): Number of protons in the nucleus; indicates element's position in the periodic table.
Mass Number (A): Total of protons and neutrons; does not determine the position in the periodic table.
Relation: Number of Neutrons (n) = Mass number (A) - Atomic number (Z).

Electronic Configuration

Distribution of electrons in orbits around the nucleus.
Examples:
- Sodium (Na): 11 electrons represented as (2, 8, 1).
- Magnesium (Mg): 12 electrons as (2, 8, 2).

Bond Types

Coordinate Bond (Dative Bond): Shared electron pair originating from one atom, indicated by an arrow (→). Examples include NH4+ and H2SO4.
Hydrogen Bond: A weak bond formed between hydrogen and electronegative atoms (e.g., F, O, N).
Intramolecular Hydrogen Bonds involve attractions within a single molecule, while Intermolecular bonds occur between different molecules.

Properties of Hydrogen Bonding

Weaker than ionic and covalent bonds.
Compounds with hydrogen bonding often have higher melting and boiling points.
Essential for the stability of certain crystalline forms.

Types of Solids

Crystalline Solids: Highly ordered structures with a specific geometric arrangement. Defined by unit cells.
Amorphous Solids: Random particle arrangement, lack sharp melting points; examples include glass and plastic.

Crystal Lattice and Unit Cell

Crystal Lattice: 3D structure formed by the arrangement of atoms or molecules.
Unit Cell: Smallest repeating unit in a crystal; contributes to the properties of the entire crystal.
Coordinate Number: The total number of atoms or ions surrounding a given atom in a crystal lattice.

Types of Crystal Structures

Simple Cubic (SC): Atoms at corners of a cube. Coordination number = 6.
Body Centered Cubic (BCC): Atoms at the corners and one in the center. Coordination number = 8.
Face Centered Cubic (FCC): Atoms at corners and centers of each face. Coordination number = 12.
Hexagonal Close Packed (HCP): Compact arrangement with a different geometric configuration.

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Description

This quiz explores the concept of electrovalency, focusing on how elements like sodium, magnesium, calcium, and chlorine gain or lose electrons to achieve stability. Understand positive and negative electrovalency through reactions and electron configurations. Test your knowledge on ionic charges and electron transfers.