Chapter 1 L02

Question 1

Why is the atomic weight not equal to the multiple of protons and neutrons?

Answer 1

Atomic weight represents an average mass of all the isotopes of an atom

Question 2

How many elements are there in the periodic table

Answer 2

92. From Hydrogen to Uranium

Question 3

Difference between atomic number and atomic mass?

Answer 3

Atomic number: number of protons
Atomic mass: mass given by number of protons and neutrons (unit: amu)

Question 4

What is an isotop?

Answer 4

Atom of same element but different number of neutrons

Question 5

How is the energy of electrons?

Answer 5

The Energy is quantified, only specific values are allowed. [eV]

Question 6

Comparison of Bohr and wave-mechanical models

Answer 6

Bohr: Assumes electrons are located at well defined orbits
Wave-Mech: Gives a probability

Question 7

Difference between shell and orbital of an atom

Answer 7

• Shell: Energy levels where electronas are founf
• Orbital: Area inside the shell where it is likely to find an electron

Question 8

What denotes the principal quantum number n=(1,2,…)?

Answer 8

Shells. Distance electron-nucleus

Question 9

What denotes the 2° quantum number (s,p,d,f)?

Answer 9

Sub-shells (orbitals) and its form

Question 10

What denotes the 3° quantum number?

Answer 10

Parcial orientation of electron

Question 11

What denotes the 4° quantum number?

Answer 11

Magnetic spin of electron

Question 12

What are a Valence electrons?

Answer 12

Electrons in the most outemost filled shell.They participate in the bounding of atoms

Question 13

How is electronegativity defined?

Answer 13

Describes the attraction of the atom’s nucleus to an external electron

Question 14

Name the 3 elementary bounding mechanisms

Answer 14

Metallic, Covalent and Ionic bonds

Question 15

What are the 2 types of forces between atoms?

Answer 15

• Attraction and Repuslion
• f (distance)

Question 16

What happens to the outer electron shells when two atoms begin to overlap?

Answer 16

A strong repulsion force appears

Question 17

How is the net force defined?

Answer 17

FR = FN+FA

Question 18

Name 3 characteristics of Ionic bonding

Answer 18

• Atom of high electroneg. takes neutron from an atom of lower electroneg.
• They form a lattice* (crystalline structure)
• Hard and brittle

Question 19

Name 3 characteristics of Covalent bonding

Answer 19

• Share at least one valence electron. Similar electroneg.
• High energy and stabel bounds
• Hydrogen bounds are Covalent bounds

Question 20

Name 3 characteristics of Metallic bonding

Answer 20

• Valence electrons are shared in a “cloud”
• Positive charged atoms form a lattice structure
• ↑ Thermal and electrical conductivity

Question 21

How are Van der Waals Bonds formed?

Answer 21

Attraction between dipoles