PERIODICITY Flashcards
What is the definition of covalent radii?
Half the distance between two bonding nuclei.
What is the covalent radii trend going down a group?
As you go down a group the trend is to increase, this is because there is an extra shell being added.
What is the covalent radii trend going across a period?
As you go across a period the trend is to decrease, this is because of the increasing attraction between the electrons and the nucleus. This causes the outer shell to be pulled closer.
What is the definition of ionisation energy?
The energy required to remove one mole of an electron from one mole of an atom in the gaseous state.
What is the ionisation energy trend going down a group?
As you go down a group the trend is to decrease, this is because an extra shell is being added each time making the outer shell further from the nucleus. Shielding effect makes the outer electrons easy to remove.
What is the ionisation energy trend going across a period?
As you go across a period the trend is to increase, this is because of the nuclear charge. The increased attraction between the outer electrons and the nucleus makes them harder to remove.
Is the ionic or atomic radii of metals larger?
The atomic radii of metals are always considerably larger than the ionic radii, this is because there is one less shell in the ion and the increases electrostatic attraction causes the outer shell to more closer to the nucleus.
Is the ionic or the atomic radii of non-metals larger?
The ionic radii of non-metals are always considerably larger than the atomic radii, this is because they are gaining electrons increasing shielding effect.
What is the definition of electronegativity?
The definition of electronegativity is the attraction an atom which is involved in a covalent bond has for a shared pair of electrons
Why does sodium have a higher melting point than magnesium?
Metallic bonding is present in both sodium and magnesium which is the electrostatic attraction between the positive ions and the sea of delocalised electrons
Sodium has a greater nucleur charge and is closer to the nucleus than magnesium and less shielding
This means sodium requires more energy which is why sodium has a higher melting point.
Why does calcium have a higher melting point than potassium?
There is metallic bonding present in both calcium and potassium which is the electrostatic attraction between positive ions and a sea of delocalised electrons
Calcium has a greater nucleur charge and is closer to the nucleus, calcium also has an extra electrons meaning more shielding effect.
This means calcium requires more energy. Therefore, it has a higher melting point.
