chapter 8- periodicity Flashcards
(22 cards)
what are metalloids
elements that sit on the staircase from metals to non-metals, with both metal and non-meta properties
what is a characteristic of transition metals
metals that form compounds with partly filled d-orbitals
why are transition elements and d-block elements not exactly the same
because some elements do not form any compounds which have partly filled d-orbitals
what if the order of reactivity is the s-block
more reactive going down the group
what is the order of reactivity for non-metals
less reactive going down a group
why is it hard to place helium
because its properties are similar to that of the nobel gases but it is not a p-block element
why is it hard to place hydrogen
because it forms singly charged 1+ (H+) ions like group one elements but is not a reactive metal like group 1 instead it is a gas
what structure do elements of period 3 group 1,2,3 form
Giant metallic structures
what structure does silicon form
giant covalent structure
what structure does phosphorus, sulfur and chlorine form
simple covalent structures
what is the melting and boiling points like for the giant metallic structures is period 3
high melting and boiling points
what are the melting and boiling points for simple covalent structures in period 3
low melting and boiling points
what does m.p and b.p increase across period 3 from sodium to aluminum
because of the strength of the metallic bonding, as you go from left to right the charge of the ion increases so more electrons join the delocalised electron sea that holds the giant lattice together, increasing the electrostatic attraction
what does the m.p and b.p of non-metals with molecular structures depend on
the size of the Van Der Waals forces between the molecules, which depends on the Mr oft the molecules and the number of electrons in the molecule and how closely molecules can pack together
how do you measure the radius of an atom
by halving the distance between the centers of a pair of atoms
what happens to atomic radius across a period and why
across a period the atomic radius decreases, because more protons are added to the nucleus increasing the nuclear charge, without increasing the amount of electron shells as they are added to the same energy level
what happens to the atomic radii of atoms down a group
the atomic radii increases as each atom has one extra complete main level of electrons, so the main level is further away from the nucleus
what is ionisation energy
the energy required to convert a mole of gaseous atoms into a mole of positively charges gaseous ions
(to remove one electron from each atom)
what happens to first ionisation energy across a period and why
the first ionisation energy increases across a period as the number of protons in the nucleus increases, increasing nuclear charge
what happens to first ionisation energy down a group and why
it decreases as the number of filled energy level increases resulting in an increased shielding, so less attraction between the nucleus and outermost electron
why does the first ionisation energy drop across a period between group 2 and 3
this is because the outermost electron on group 2 is on an s-orbital whereas on group 3 its on a p-orbital. since the p-orbital is a higher energy level there is less attraction between the electron and nucleus
why does the first ionisation energy decrease across a period between groups 5 and 6
this is because group 6 atoms have an electron pair in its outermost orbital causing a repulsion making it easier for the electron to be removed. in comparison to group 5 atoms which have no paired electrons making it harder from them to be removed
