Topic 3-Atomic Structure Flashcards
What is chemistry?
Chemistry is the study of matter
What was Democritus’ contribution to the atomic theory?
Democritus was the first to propose that matter was made up of indivisible particles.
What does the word “atom” in greek mean?
“Atom” means “uncuttable” in greek.
What is the Law of Conservation of Mass?
The Law of Conservation of Mass states that matter is neither created nor destroyed.
What is the Law of Constant Composition?
The Law of Constant Composition states that a given sample of a compound always contains the same fraction of elements by mass.
What is the Law of Multiple Proportions?
The Law of Multiple Proportions states that when two elements form more than one compound, the masses of the elements are in simple ratios.
What was J.J Thomson’s contribution towards the Atomic Theory (1897)?
He found out 2 things:
- An electron is a fundamental particle of all atoms
- Electrons possess a mass
What was Rutherford’s model of the atom called (1910)? What did it state?
Rutherford proposed the “Nuclear Atom” model.
It stated two things:
1. The mass of the atom and its positive charge is condensed inside a tiny region (nucleus)
2. The atom is mostly empty space.
Which particle is considered to have a negligible mass?
An electron.
What is the definition of an isotope?
Isotopes are different atoms of the same element that have different numbers of neutrons but with the same number of protons.
What is a Mass Spectrometer?
A Mass Spectrometer is an instrument for measuring the masses of atoms and compared to their relative abundance.
In a mass spectrum reading, the number of peaks correlates with the number of what?
The number of isotopes.
What is the difference between an isotopic mass and an atomic mass?
An isotopic mass is the mass of a specific isotope.
An atomic mass is the average mass of all the isotopes combined.
What does an atomic mass unit (u) equal to?
1 atomic mass unit is equal to 1/12 of a 12C atom.
