Periodicty Flashcards
(15 cards)
What is atomic size
Chemsitry measure atomic size by measuring covalent radius of atom
Covalent radius is ?
Half the distance between the 2 nuclei of 2 bonded atoms
Atomic size decreases across a period?
Why?
Moving from 1 element to another:
•electrons are added to the same energy level & protons to the nucleus
•the outer energy levels are therefor attracted more strongly & are pulled closer to the nucleus.
Atomic size increase descending a group
Structured
Attraction
Due to
•Increase in number of energy levels, meaning outer electrons are further away from nucleus
•this means nucleus has less of an attraction on outer electrons allowing them to be further away form each other
Ionic radius relates to what
Size of an Ion
Ionisation energy
When atoms lose electrons to form ions, these electrons have to be removed
What is the 1st ionisation
1st ionisation energy of an element is the energy required to remove 1 mole of electrons from 1 mole of gaseous atoms of that element
General rule
Increase in nuclear charge pulls outer E closer to nucleus reducing size of atom
This increases strength
General rule descend
Decreases, due to outer electrons being removed is further away from nucleus so less attracted to the nucleus meaning less energy is needed to remove it
General rule descend pt2
The inner electrostatic force have a screening effect, which shields outer electrons from the pull of the nucleus
This means outer electrons to the nucleus is weaker hence the less attraction
Electronegativity
The measure of attraction an atom has for electrons in a bond
Electronegativity across a peroid
Due to the nuclear charge increasing, therefor the nucleus of an atoms has stronger pull on electrons
Atomic size down a group
Atomic size increases down a group meaning Shaired pair of electrons e are further away from the nucleus & are less strongly attracted. As the group descends number of shells increase. This increases the screening effect meaning the nuclear pull ain’t strong
