Topic 1 - Atomic Structure & The Periodic Table Flashcards
What is the radius of an atom?
0.1 nanometers (that’s 1 x 10-10 m)
What is the radius of a nuclei of an atom?
1 x 10-14 m (10,000 times smaller than the radius of an atom)
What is an isotope?
Isotopes are different forms of an element, with the same number of protons and different number of neutrons/atomic mass.
What was John Dalton’s contribution to the atom?
- Experiments led to him identifying that atoms of different elements had different atomic weights.
- He was one of the first scientists to use symbols for different elements and how compounds are produced by joining different elements together.
What did Dalton conclude about the atom?
- All matter is made up of atoms.
- Atoms can not be broken down into anything simpler (which is not true).
- Atoms are rearranged in a chemical reaction.
What was JJ Thomson’s contribution to the atom?
- He discovered the electron in 1897
This disproved Dalton’s theory that atoms could not be broken down into anything simpler. - His discovery of the electron began in 1895 with a series of experiments where he introduced the plum pudding model.
What was Rutherford’s contribution to the atom?
- In 1911 used experimental evidence to show that an atom contained a nucleus.
- He published his theory that an atom had a central positive nucleus surrounded by negative orbiting electrons.
- He suggested that most of the mass was contained in the nucleus and that rest of the atom was empty space.
- He came to this conclusion through the results of his gold foil experiment.
What can we conclude from Rutherford’s gold foil experiment?
- Most particles went straight through: meaning most of the atom is empty.
- Some particles are deflected: meaning some must be of positive charge.
- A few of them bounced straight back: meaning there is positive charge and mass concentrated in the middle of the atom.
What was Niels Bohr’s contribution to the atom?
- He developed the Bohr model of the atom which suggested that electrons orbit at set energy levels in fixed shells around the nucleus.
- He suggested that each electron can jump from one energy level or orbit to another.
- He also suggested that each shell is a fixed distance from the nucleus.
What was James Chadwick’s contribution to the atom?
He carried out a set of experiments in which the results proved the existence of the neutron.
What was John Dalton’s contribution to the periodic table?
- Experiments led to him identifying that atoms of different elements had different atomic weights.
- He was one of the first scientists to use symbols for different elements and how compounds are produced by joining different elements together.
What was Johann Döbereiner’s contribution to the periodic table?
- He carried out many investigations using known elements.
- He noticed that some elements could be grouped together because they had similar physical or chemical properties
- Most of these groups had three elements.
- At this time, some scientists discovered relative atomic masses of the elements.
- He discovered the relative atomic mass of one element was approximately the average of the other atomic masses.
- In 1817, he introduced the law of triads.
What were the problems with Döbereiner’s table?
