Topic 1-Atomic Structure & The Periodic Table Flashcards
define the term, isotope
Atoms of the same element with different number of neutrons thus different mass number
Why do different isotopes of the same element react in the same way
neutrons have no impact on the chemical reactivity
reactions involve electrons, istopes have the same number of electrons in the same arrangement
define relative atomic mass
the weighted mean mass of an atom of an element compared with one twelfth of the mass of an atom of carbon-12.
define relative isotopic mass
the mass of an atom of an isotope compared with one twelfth of the mass of an atom of carbon-12
the relative isotopic mass is same as which number
mass number
what are the uses of mass spectrometry
identify unknown compunds
find relative abundance of each isotope of an element
determine structural information
what is an orbital
a region around the nucleus that can hold up to two electrons with opposite spins
what is meant by periodicity
the repeating trends in chemical and physical properties
what change happens across each period
elements change from metals to non-metals
define first ionisation energy
the energy required to remove a mole of electrons from a mole of gaseous atoms to form one mole of gaseous 1+ ions under standard conditions.
factors that afect ionisation enrgy
atomic radius
nuclear charge
electron shielding or screening
period 3 trend
first iomisation energy increases across period 3 because of
increased nuclear charge
decreased atomic radius
same electron shieliding
this means more energy is needed to remove the first electron
does first ionisation increase or decrease down a group? why?
decrease
shielding increases–> weaker attraction
atomic radius increases–> distance between the outer electrons and nucleus increases –> weaker attraction
increase in number of protons is outweighed by increase in distance and shielding
Describe the structure, forces and bonding in every eement across period 2
Li and Be –> giant metallic; strong attraction between positive ions and delocalised electrons; metallic bonding
B and C –. giant covalent; strong forces between atoms; covalent
N2 O2 F2 NE2- simple molecular; weak intermolecular forces between molecules; covalent bonding within molecules and intermolecular forces between molecules
describe the structure, forces and bonding in every element across period 3
Na, Mg,Al–> giant metallic; strong attraction between positive ions and delocalised electrons; metallic bonding
si–> giant covalent; strong forces between atoms; covalent
p4 s8 cl2 Ar –> simple molecular; weak intermolecular forces between molecules; covalent bonding within molecules and intermolecular forces between molecules
