Topic 1 Atomic structure and periodic table Flashcards
What does an atom contain?
It contains protons and neutrons in the nucleus and electrons in orbits around.
The nucleus is where most of the mass of an atom is and it is very small. It contains protons and neutrons
Electrons orbit the nucleus in shells and take most of the space of an atom
What is the mass number and what is the atomic number?
Mass number - Tells us the number of protons and neutrons in the nucleus. (bigger number)
Atomic number - Tells us the number of protons in the nucleus (smaller number)
since all atoms are neutral - Number of protons = number of electrons
What are ions?
They have different number of electrons and protons
Negative ions have gained electrons to gain a full shell of electrons. O2-
Positive ions have lost electrons to gain a full shell of electrons. Na+
What are isotopes?
They are elements with the same number of protons but a different number of neutrons
What is relative atomic mass and the relative isotopic mass
Relative atomic mass - It is the weighted mean mass of an atom of an element, compared to 1/12th of the mass of an atom of carbon-12
Relative isotopic mass - It is the mass of an atom of an isotope, compared to 1/12th of the mass of an atom of carbon-12
What is m/z?
It is just the mass of an isotope divided by the charge
How to calc relative atomic mass?
(Abundance of A x mass/charge ratio) + (Abundance of B x mass/charge ratio) / 100
How to predict mass spectra?
- Write the %’s as decimals
- Create a table showing the isotope combinations in a molecule. Multiply the decimal form of abundance of each isotope to get the relative abundance of each molecule
- Any molecules which are the same add the abundances up
- Divide all the relative abundances worked out before by the smallest value. This will give you a whole number ratio which can be used to predict your spectra
What do the peaks show on a mass spectra molecule version?
Peaks show fragments of the original molecule. The last peak is the M+1 peak or the molecular ion peak. This is the same as the relative molecular mass of the molecule
What subshells are electron shells split into? and how many orbitals do they have and how many electrons can they hold?
S P D F
S shell - Contains 1 orbital which holds 2 electrons
P shell - Contains 3 orbitals and can hold 6 electrons
D shell - Contains 5 orbitals and can hold 10 electrons
F shell - Contains 7 orbitals and can hold 14 electrons
What is the shape of the s orbital?
The s orbital is spherical and the 2 electrons can move anywhere within this sphere
What is the shape of the P orbital?
There are 3 p orbitals in the shape of dumbbells and can hold up to 2 electrons. They are 90 degrees to each other.
What is the order of electronic configuration?
1s2 2s2 2p6 3s2 3p6 4s2 3d10
You fill orbitals singly and then we pair up. This is due to electron repulsion.
Electron configuration of ions
For ions, you just add or remove from the highest energy level first
Ca2+ = would lose 2 electrons from the 4s
Electron configuration of transition metals
Chromium and copper behave differently
An electron from the 4s orbital moves into the 3d orbital to create a more stable half-full or full 3d sub shell
Same thing with iron. Fe3+ loses 3 electrons, 2 from the 4s and 1 from the 3d