Atomic Structure Flashcards
What structure is in the centre of an atom?
Nucleus
Name the two sub-atomic particles within the nucleus.
Protons and Neutrons
What are protons and neutrons collectively known as?
Nucleons
What is around the outside of the nucleus?
Electrons
What type of charge do each if the three sub-atomic particles have?
Protons - +ve
Nuetrons - nuetral (0)
Electrons - -ve
What is the (usually) the overall charge of the atom and why is that?
The overall charge of an atom is usually neutral because there is the same number of electrons as protons.
What is the symbol for atomic number?
Z
What is the atomic number?
Number of protons
What is the symbol for mass number?
A
The formula for mass number?
Protons + Neutrons = Mass number (A)
What is on top of the chemical symbol and what is on the bottom?
Top - Mass Number (A)
Bottom - Atomic Number (Z)
Define Electrons
Electrons are small light particles that orbit the nucleus. They are arranged in shell around the nucleus, with each shell containing a maximum number of electron it can hold.
Which shell is always filled first?
The innermost shell is filled first then follows the second inner shell and so on.
What are the first four shells referred to as?
1 - K
2- L
3 - M
4 - N
What is the outer most shell referred to as?
Valence Shell
State the four properties the valence shell determines.
Chemical, Thermal, Optical and Electrical
Why is copper a good conductor of heat and electricity?
There is one electron in the valence shell which easily leaves the atoms allowing it to act as a free electron.
State the group number of noble gasses.
Group 18
Give me three examples of Nobles Gases
Any of the three - Helium, Neon, Argon, Xenon, Krypton, Radon and Ogenessan
What noble gas is used for cooling MRI scanners?
Helium
What does it mean when noble gases are inert and why are they this way?
Inert means noble gases are less to non - reactive due to their valence shell being full
How are electrons held in their shell?
They are held by a binding energy due to the electrical charges of both the electrons and protons.
What determines the strength of the binding energy?
The closer the shells is to the nucleus, the stronger its binding energy, e.g. the binding energy of K shells is stronger than L shell
What is the unit of measurement of binding energy?
keV (kiloelectronvolt)
State the binding energy of a tungsten atom (from K to M) - include their number of electrons.
K - 70 keV - 2
L - 11 keV - 8
M - 2 keV -18
What makes an atom electrically stable?
When there is the same amount of electrons and protons, which cancels out allowing them to be stable.
What happens when an electron is removed from an atom?
The protons with outnumber the remaining electrons leaving the atom with a net positive charge. This process is called ionisation, and in this case the ionised atom is known as a positive ion.
What needs to happen for an electron to be removed from its shell?
The binding energy has to be overcome for an electron to be removed. The more protons in the nucleus the higher the binding energy required to remove an electron , as well as the close the shell to the nucleus, the higher the binding energy.
How are x - rays created?
X - rays are created when atoms are ionised by free electrons - the kinematic energy within the free electron transfers to overcome a bound electron’s binding energy.
What happens when atoms in the body get ionised?
Atoms in the body can be ionised by x - ray photons, this leads to chemical changes occurring which can cause permanent damage
What is an isotope.
An atom that has the same atomic number (Z) but a different mass number (A) - as the number of neutrons can vary.
State the two ways isotopes occur.
Naturally or Artificially
Give two examples of isotopes
Technetium - 99m (used for nuclear med.)
Cobalt - 60 (used for gamma knife)
