The Structure of an Atom

Question 1

Basic structural unit of an element that retains chemical properties

Answer 1

Atom

Question 2

Consists of different subatomic particles

Answer 2

Atom

Question 3

4 subatomic particles

Answer 3

• electrons
• nucleus
• protons
• neutrons

Question 4

Negatively charged subatomic particle (outside nucleus)

Answer 4

Electron (e-)

Question 5

Small and dense center of an atom

Answer 5

Nucleus

Question 6

Positively charged subatomic particle

Answer 6

Proton (p+)

Question 7

Uncharged subatomic particle

Answer 7

Neutron (n0)

Question 8

A pure substance that cannot be broken down into simpler substances by a chemical reaction

Answer 8

Element

Question 9

atoms of the same element having different masses

Answer 9

isotopes

Question 10

The weighted average of the masses of all the isotopes that make up the element

Answer 10

Atomic mass

Question 11

A theory based on the law of conservation of mass and Law of definite proportions

Answer 11

John Dalton’s Atomic theory

Question 12

• All matter consists of tiny particles called atoms
• An atom cannot be created, divided, destroyed, or converted to any other type of atom
• Atoms of a particular element have identical properties

Answer 12

John Dalton’s Atomic Theory

Question 13

• Atoms of different elements have different properties
• Atoms of different elements combine in simple whole-number ratios to produce compounds (stable combinations of atoms)
• Chemical change involves joining, separating, or rearranging atoms

Answer 13

John Dalton’s Atomic Theory

Question 14

4 individuals who found evidences of subatomic particles

Answer 14

• J.J Thomson (1897)
• Robert Millikan (1910)
• Ernest Rutherford (1897-1920)
• James Chadwick (1920 - 1932)

Question 15

• Cathode ray tube experiment
• Cathode rays are stream of negative
  particles of energy
• discovered electrons

Answer 15

J.J Thomson (1897)

Question 16

• oil-drop experiment
• identified the magnitude of mass and charge of the electron

Answer 16

Robert Millikan (1910)

Question 17

• “Gold Foil Experiment” lead to the understanding of the nucleus
• Most alpha particles pass through the foil without being deflected

Answer 17

Ernest Rutherford (1897 - 1920)

Question 18

• Some particles were deflected, a few even directly back to the source
• interpreted that an atom is empty space and most of the mass and positive charge (protons) must be located at the small and dense region (nucleus).

Answer 18

Ernest Rutherford (1897 - 1920)

Question 19

• bombarded Beryllium with alpha particles from the natural radioactive decay of Polonium
• concluded that the unusually penetrating radiation consisted of uncharged particles having (approximately) the same mass as a proton (neutrons).

Answer 19

James Chadwick (1920 - 1932)

Question 20

• In 1913, _____ proposed a theory for hydrogen atom.
• Atoms can absorb and emit energy via promotion of electrons to higher energy levels and relaxation to lower levels

Answer 20

Neils Bohr’s Atomic Theory

Question 21

• Electrons are found in allowed energy levels (quantized energy levels, or orbits)
• Energy that is emitted upon relaxation is observed as a single wavelength of light

Answer 21

Neils Bohr’s Atomic Theory

Question 22

light emitted when a substance is excited by an energy source

Answer 22

Emission spectrum

Question 23

• Emission spectrum - light emitted when a substance is excited by an energy source
• Spectral lines are a result of electron transitions between allowed levels in the atoms
• The emission spectrum of hydrogen led to the modern understanding of the electronic structure of the atom.

Answer 23

Neils Bohr’s Atomic Theory

Question 24

An atomic Model proposed by Erwin Shrodinger (1887 - 1961)

Answer 24

Quantum Mechanical Model

Question 25

• used the wave-particle duality of the electron based on quantum theory
• describes the probability of finding electrons to a region of space within the principal energy level (atomic orbital)

Answer 25

Erwin Shrodingern (1887 - 1961)