History of the Atom

Which scientist used this apperatus?

Ernest Rutherford

Which scientist used this apperatus?

JJ Thomson

Which of the following choices correctly characterizes the Nuclear (Rutherford's) atomic model?

There are two subatomic particles (the electron and the proton), and these particles are each localized in a specific region (protons in the nucleus, and electrons scattered around the nucleus randomly).

Which of the following choices correctly characterizes the Plum Pudding (Thomson's) atomic model?

There is one subatomic particle (the electron), and these particles are spaced randomly in a positive region.

What does it mean if most of the alpha particles passed directly through the gold foil?

Most of the atom is empty space

What does it mean if some of the alpha particles rebounded backwards

The atom has a dense postive nucleus

What does it mean if the particle beam bent away from the negative magnetic pole?

The particle beam must have a negative charge

Used the Gold-Foil experiment to determine that each atom has a dense, positively-charged nucleus in its center

Rutherford

Gathered evidence for the existence of atoms, and believed the atom to look like a solid sphere. 

Dalton

Identified a neutral particle of roughly the same size as the proton in the nucleus of the atom

Chadwick

Used light emission spectra to determine that electrons are likely found in fixed/defined energy levels around the nucleus. Believed that electrons orbited the nucleus on these energy levels just as the planets orbit the sun.

Bohr

Identified the first subatomic particle, the negatively charged electron 

Thomson

Which of the following correctly characterizes Dalton's atomic model?

Atoms can be combined, separated, and rearranged during chemical reactions

Which of the following correctly characterizes Rutherford's groundbreaking experiment?

The gold foil experiment led directly to the discovery of the atomic nucleus

Who made the solid sphere model in 1803?

John Dalton

The first thing that Dalton proposed was

all matter is made up small solid spheres

The second thing that Dalton proposed was

Atoms cannot be broken down into smaller parts

The third thing that Dalton proposed was

all of the atoms of a specific element are exactly alike

What was Thomson’s apperatus/ expeirment of the atom?

The Cathode ray tube

What is Thomson’s first inference?

There are subatomic particles within atoms that have a negative charge (electrons)

What is Thomson’s second inference?

Electrons are randomly spaced throughout the atom

What is Thomson’s third inference?

The atom itself is a postively charged sphere

Thomson’s model name is “Plum Pudding Model” because…

• Positively charged “pudding”

• Negatively charged “raisins” (electrons)

Who made the Plum Pudding Model in 1904?

Thompson

Wo made the nuclear model in 1911?

Ernest Rutherford

Who made the planetary model in 1913?

Niels Bohr

Who made the Quantum model in 1926?

Erwin Schrodinger

What was Ernest Rutherfords apperatus/expeirment of the atom?

• Gold Foil Experiment

  • Shot “alpha particles” (positively charged particles) through a thin gold foil sheet surrounded by a detection screen

This is Neils Bohr’s model of the atom, what does this show us?

Bohr observed specific wavelengths (colors) of light when electricity was applied to a hydrogen gas tube.

This is Erwin Schrodinger’s Model of the Atom, what does it show us?

Electrons in probability regions (orbitals) around the nucleus

Schrodinger used mathematical functions to determine the arrangement of electrons around the nucleus

Who made the atomic emissions spectrum?

Bohr

Who discovered the neutron?

Chadwick

What is Dalton’s model’s name?

The soild sphere model

Where did Dalton think protons were located?

The whole atom is one big proton

Where did Dalton think was the location of electrons?

There is no electrons.

What was Daltons experiment?

Bilards ball model- Came up with 5 postulates about atoms:

1. Atoms are the smallest, indivisible pieces of matter.

2. All atoms of the same element are identical.

3. Atoms of different elements are always different.

4. Atoms combine in whole-number ratios to form compounds (no half atoms in a compound)

5. Chemical reactions involve the rearrangement of atoms.

What is Thomson model name?

Plum Pudding model

Where did Thompson think protons where located?

Whole atom is one proton

Where did Thompson think electrons were loacted?

Random spaced throughout the protons

What was Thomsons experiment?

CATHODE RAY TUBE

• Particles in cathode tube attracted to positive (+) magnet

  • THEREFORE Particles must be negative             → found electrons

What was Rutherfords model name?

The nuclear model

Where did Rutherford think protons were located

In the nucleus

Where did Rutherford think electrons were located

Randomly scatered throughout the atom

What was Rutherfords experiment?

GOLD FOIL EXPERIMENT

• Positive Alpha particles shot through gold foil

• 99% of particles didn’t hit anything

  • THEREFORE atom is mostly empty space

• Some particles were repelled 

  • Positive nucleus repelled by positive alpha particles

What is Bohr model name

The Bohr model

Where did Bohr think protons were?

In the nucleus bohr

Where did Bohr think electrons were?

Organised in energy levels

What was Bohr’s experiment

Light Emission Spectra

• Atoms emit light only at certain wavelengths / energies

  • Energy corresponds to a specific distance from nucleus

What was Schrodingers model name?

The quantum mechanical model

Where did Schrodinger think protons were?

In the nucleus

Where did Schrodinger think electrons were?

In probablity regions (orbitals) around the nucleus

What was Schrodingers experiment?

Math- he is smarter than we are

Plum Pudding Model-Thomson

• Discovered electrons

  • Can be removed from atom

  • Protons unknown

Nuclear Model-Rutherford

• Discovered Dense Positive Nucleus

• Discovered Atom is mostly empty space

Planetary Model-Bohr

• Discovered electron orbits

  • Electrons can only be in certain spots

Quantum Mechanical Model-Schrodinger

• Discovered electron cloud

  • Shells, Subshells, orbitals, and spins

What is a isotope?

An isotope is an atom of the same element with the same number of protons but a different number of neutrons.

Why does the periodic table list the atomic mass as instead of a whole number?

The atomic mass is a weighted average of all naturally occurring isotopes of that element based on their abudence.