DAILY QUESTION September 29, 2008 1. Who’s atomic theory is considered the foundation for the modern atomic theory?

Agenda 9/29/08 Daily Question Chapter 4 - Introduction Assignments: 1. No Assignments Tonight.

Atomic Theory Timeline ~ Year ~ Scientist ~ Contribution 1800 500 BC 1935

Atomic Theory Timeline ~ Year ~ Scientist ~ Contribution Erwin Schrodinger: Building on de Broglie's idea that electrons act like waves in some situations, he developed the basic equation of quantum mechanics in 1926. Sir Ernest Rutherford – In 1909, he constructed the first nuclear model of the atom, a cornerstone of present-day physics. In 1919, he proved the nucleus could be breached Dmitry Medeleyev – In 1871, he revealed the basic importance of atomic weights and of nuclear structure. Louis de Broglie: He proposed in 1924 that electrons could behave as waves under some conditions, a finding that helped scientists understand that the atom didn't behave like the solar system because electrons do not move in regular orbits. Democritus: In 4th century BCE (460 BC), he suggested that the universe was made of invisible units called atoms. The word atom is derived from the Greek word meaning “unable to be divided.” Werner Heisenberg: In 1927 he proposed that it is impossible to know the position and velocity of an electron at the same time; this concept is called the uncertainty principle. 1800 500 BC 1935 John Dalton: In 1808 proposed the atomic theory. According to Dalton, all atoms of a given element were exactly the same and the atoms could join to form compounds. Niels Bohr: In 1913, he proposed a model of the atom with electrons orbiting the nucleus similar to the planets revolving around the sun. The orbits of electrons depend on their energy, and electrons can jump from one energy level to another; and energy travels in discrete quantities. James Chadwick and E.S. Bieler: They proposed in 1921 that a strong force held the nucleus together. In 1932, Chadwick discovered the neutron, a particle with no electrical charge. Sir J.J. Thomson – In 1897, the English physicist explained the nature of the electron. Max Born: Working with Heisenberg in 1927, Born modified Schrodinger's equation of quantum mechanics. His idea helped scientists develop the model of an atom with a nucleus surrounded by electrons at different locations when they are in different energy states.

Developing the Atomic Theory Democritus: In 4th century BCE (460 BC), he suggested that the universe was made of invisible units called atoms. The word atom is derived from the Greek word meaning “unable to be divided.” John Dalton: In 1808 proposed the atomic theory. According to Dalton, all atoms of a given element were exactly the same and the atoms could join to form compounds.

Developing the Atomic Theory Dmitry Medeleyev – In 1871, he revealed the basic importance of atomic weights and of nuclear structure. Sir J.J. Thomson – In 1897, the English physicist explained the nature of the electron. Sir Ernest Rutherford – In 1909, he constructed the first nuclear model of the atom, a cornerstone of present-day physics.

Developing the Atomic Theory Niels Bohr: In 1913, he proposed a model of the atom with electrons orbiting the nucleus similar to the planets revolving around the sun. The orbits of electrons depend on their energy, and electrons can jump from one energy level to another; and energy travels in discrete quantities. James Chadwick and E.S. Bieler: They proposed in 1921 that a strong force held the nucleus together. Louis de Broglie: He proposed in 1924 that electrons could behave as waves under some conditions, a finding that helped scientists understand that the atom didn't behave like the solar system because electrons do not move in regular orbits.

Developing the Atomic Theory Erwin Schrodinger: Building on de Broglie's idea that electrons act like waves in some situations, he developed the basic equation of quantum mechanics in 1926. Werner Heisenberg: In 1927 he proposed that it is impossible to know the position and velocity of an electron at the same time; this concept is called the uncertainty principle. Max Born: Working with Heisenberg in 1927, Born modified Schrodinger's equation of quantum mechanics. His idea helped scientists develop the model of an atom with a nucleus surrounded by electrons at different locations when they are in different energy states.

Atoms (page 104-105) The smallest part of an element that still has the element’s properties Combine to make molecules Examples: H2O Whether 1 molecule or billions, they are always the same: 2 hydrogen to 1 oxygen

What’s in an Atom? (page 106) Positive Charge Negative Charge No Charge Found in Nucleus Found in Nucleus Found surrounding Nucleus Very little mass Same mass as a proton Same mass as a neutron Same size as a proton Same size as a neutron Very small size Subatomic particles Proton Neutron Electron