Question

atomic theory concept check
name: marylie

1. fill in the table with a brief description of each scientists contribution to atomic theory.

democritus: first to propose the idea of atoms
dalton: create the first atomic theory
thomson: discover the electron
millikan: determine the mass and charge of an electron
planck: determine that energy can be measured in units of \packets\
rutherford: discover matter is mostly empty space
bohr:
heisenberg:
de broglie:
schrodinger:

1. what are the four parts of daltons theory? indicate which parts are no longer accepted as correct.

Explanation:

1. Bohr: Proposed a model of the atom with electrons in fixed - energy orbits.

Heisenberg: Formulated the uncertainty principle.
De Broglie: Suggested that electrons have wave - like properties (wave - particle duality).
Schrodinger: Developed wave mechanics and the Schrodinger equation to describe the behavior of electrons in an atom.

1. The four parts of Dalton's theory are:

• All matter is made of atoms, which are indivisible and indestructible. The idea that atoms are indivisible is no longer correct as we know about sub - atomic particles (protons, neutrons, electrons).
• All atoms of a given element are identical in mass and properties. Isotopes show that atoms of the same element can have different masses.
• Compounds are formed by a combination of two or more different kinds of atoms. This part is still generally accepted.
• A chemical reaction is a rearrangement of atoms. This part is still valid.

Answer:

1. Bohr: Proposed atomic model with electron orbits.

Heisenberg: Uncertainty principle.
De Broglie: Electron wave - like properties.
Schrodinger: Wave mechanics and equation for electrons.

1. Parts of Dalton's theory:

• All matter is made of indivisible atoms (Indivisibility is incorrect).
• All atoms of an element are identical (Incorrect due to isotopes).
• Compounds are formed by atom combination (Accepted).
• Chemical reactions are atom rearrangements (Accepted).