Module 2.1- Atoms and Reactions Flashcards
(19 cards)
What did Democritus suggest about atoms?
He developed the first idea of the atom
Suggested that if you continued to split a sample of matter you would eventually end up with an atom that cannot split any further
Explain Dalton’s atomic theory
Dalton stated that atoms are tiny particles of solid hard spheres that make up elements and cannot be divided
Suggested that all atoms of a given element are the same and atoms of one element are different from those of other elements
What did JJ Thompson discover? How?
Thomson discovered electrons
What did Rutherfords Gold leaf experiment show?
What did Neil’s Bohr discover?
In 1918 Rutherford discovered the…
How was Henry Moselys discovery explained by Rutherfords discovery of the proton?
Moseley discovered a link between X ray frequencies and an elements atomic number. Proving that each element has a different positive charge in the nucleus. and Rutherford’s discovery of the proton was able to explain this finding.
Compare the Plum pudding model, and Rutherfords nuclear model of the atom
How did Bohrs planetary model differ from previous models of the atom?
What did Louis de Broglie and Erwin Schrödinger suggest ?
de Broglie- suggested that particles could have the nature of both a wave and a particle
Schrödinger- suggested that an electron had wave like properties in an atom. Also introduced ideas of atomic orbitals
What did James Chadwick discover?
Complete table of relative mass and charge of Protons Neutrons and electrons
Relative mass Relative charge
P 1 +1
N 1 0
E 1/1836 -1
What is an isotope
Isotopes are atoms of the same element have the same atomic number but a different mass number
(Same number of protons, different number of neutrons)
Chemical properties of isotopes are
Physical properties of isotopes are
Identical (Eg reactivity)
Can differ (eg density, boiling points)
What is the significance of Carbon-12
Carbon 12 , the unified atomic mass unit (u)
An atom of 12C has a mass of 12u.
u= 12C/12 =1.66x10-27 kg
What is relative isotopic mass?
The mass of an atom of an isotope compared with 1/12 of the mass of C-12 (u). Equivalent to the mass number of the isotope
What is Relative atomic mass (Ar)
The weighted mean mass of an atom of an element compared with 1/12 of the mass of carbon 12 (u)
Silicon consists of 28-Si (92.2%), 29-Si (4.7%) and 30-Si (3.1%). What is the Ar?
0.922x28=25.816
0.047x29=1.363
0.031x30=0.93
25.816+1.363+0.93=28.109
Ar= 28.11 (2dp)
Ne has 2 isotopes 20-Ne and 22-Ne which gives an Ar of 20.18. What is the % of the 2 isotopes?
20x/100 + 22(100-x)/100 = 20.18
20x + 2200- 22x = 2018
2200 - 2x = 2018
182= 2x
91 =x
So 91% 20-Ne and 9% 22-Ne
