Flashcards in Atomic Structure Deck (17):
What charge is a nucleus, electron and an atom?
Nucleus - positively charged
Electron - negatively charged
Atom - neutral
What is the atomic number?
Number of protons in an atom
What is the mass number?
The total number of protons and neutrons in an atom
Explain why a substance is an element?
Because it cannot be broken down chemically and contains only one type of atom
Describe the main stages in the development of atomic structure illustrating the provisional nature of evidence
- Dalton's atomic theory
- J.J. Thompson (discovery of the electron)
- Rutherford (nuclear atom)
- Bohr (electron orbits)
What is a nucleus made from?
Protons and neutrons
Recall the relative charge and relative mass of an electron, a proton and a neutron
- electron charge -1 and mass 0.005 (0)
- proton charge +1 and mass 1
- neutron charge 0 and mass 1
Varieties of an element that have the same atomic number but different mass numbers
Describe the arrangement of elements in the Periodic Table
- Columns are called groups, rows are called periods
- elements in the same group have the same number if electrons in the highest occupied energy level (outer shell)
Explain the identity of an element can be deduced from its electronic structure
1. Find the element in the periodic table. Work out which period it is in, and draw that number of circles around the nucleus
2. Work out which group the element is in and draw that number of electrons in the outer circle
3. Fill the other circles with electrons
4. Count your electrons and check that they equal the atomic number
Describe Dalton's atomic theory snd how the work or J.J.Thompson, Rutherford and Bohr contributed to the development of the theory of atomic structure
- the theory changed as new evidence was found
- science explanations are provisional but more convincing when predictions are later confirmed
Explain why an atom is neutral in terms of its sub-atomic particles
Atoms contain 3 sub-atomic particles, the number of electrons in an atom is always the same as the number of protons, so atoms are electrically neutral overall.
What is the radius and mass of an atom?
Mass - 10⁻²³g
Identify isotopes from data about the number of electrons, protons and neutrons in particles
Isotopes have the same atomic number but a different mass number
Deduce the electronic stricture of the first 20 elements in the periodic table
Explain the significance of the work of Dalton, J.J. Thompson, Rutherford and Bohr in the development of the theory of atomic structure
- unexpected results (e.g, Geiger and Marsden's experiment) led to the theory of a nuclear atom