Structures and Properties

Question 1

What aspects of Medeleev’s Periodic Table do we still use today?

Answer 1

Elements are arranged mostly from smallest to largest mass.

Question 2

State the modern Periodic Law.

Answer 2

Elements are ordered by increasing atomic number and thus show repeated patterns of properties.

Question 3

Difference between mass number and average atomic mass

Answer 3

Mass Number (A) is the sum of protons and neutrons and has no units. Average Atomic Mass is the average mass of all its isotopes and has units of amu or U.

Question 4

Dalton

Answer 4

Proposed first “modern” atomic model with his atomic theory:

• All matter is composed of tiny solid spheres called atoms
• Atoms are indivisible/indestructible
• Each element has identical atoms

Question 5

Rutherford

Answer 5

Discovered the nucleus with his gold foil experiment:

• positively charged
• small
• dense
• most of the atom is empty space

Question 6

Thomson

Answer 6

Developed raisin-bun model:

• discovered electron, which is negative
• atoms are neutral
• positive sphere with electrons embedded in it

Question 7

Chadwick

Answer 7

• Discovered the neutron

- atoms of the same element with different numbers of neutrons are isotopes

Question 8

Bohr

Answer 8

• electrons move in predictable orbitals with energy levels

Question 9

Einstein

Answer 9

• a packet of energy is called a quantum (pl. quanta)
• quantum of light is called a photon
• energy is a steady stream of quanta

Question 10

Schrodinger

Answer 10

• developed mathematical models to describe electrons as particles behaving like waves
• quantum numbers and energies of electron orbitals (regions of probability of finding an electron)

Question 11

Heisenberg

Answer 11

Heisenberg’s Uncertainty Principle: It is impossible to simultaneously know the exact position and speed of a particle (electron)

Question 12

Difference between intermolecular and intramolecular forces

Answer 12

Intermolecular forces occur between atoms/ions of different molecules
Intramolecular forces occur between atoms or ions within a molecule

Question 13

Examples of intramolecular forces and intermolecular forces and the types if changes they produce

Answer 13

Intramolecular forces: ionic bond, covalent bond, polar covalent bond, chemical change
Intermolecular forces: London Dispersion, Dipole-dipole, hydrogen bonds, physical change

Question 14

Which element has the highest electronegativity?

Answer 14

Fluorine - F