Periodic Trends Flashcards
What determines if an ionic bond will form?
A large electronegativity difference between two atoms results in an ionic bond. A small electronegativity difference results in a polar covalent bond. If the atoms have the same electronegativity ( no electronegativity difference ) they tend to form non-polar covalent bond
what do the groups (columns) of periodic table represent?
what do the periods (rows) of periodic table represent?
The columns of the periodic table are called groups.
- The groups (columns) have the same set of elements with the same valence electron configuration
- both have similar bonding
The rows of the periodic table are called periods.
- The periods (rows) All the elements in a period have valence electrons in the same shell. The number of valence electrons increases from left to right in the period. When the shell is full, a new row is started and the process repeats
- Periods correspond to the relationship of orbitals, or likely areas in which electrons will be found, inside the outermost shell of the atom. Successive periods down the table correspond to atoms with a more electron-rich core of inner shells.
What is Electronegativity
Electronegativity is a chemical property that says how well an atom can attract electrons towards itself. The electronegativity of an atom is influenced by the atom’s atomic number and the distance between the atom’s valence electrons It was first theorised by Linus Pauling in 1932.
what is the electronegativity trend?
what is the most electronegative element
Ionic vs covalent bonds
Covalent bonding involves the sharing of electrons between two or more atoms.
Ionic bonds form when two or more ions come together and are held together by charge differences.
- electron affinities of two atoms differ a lot
- halogens have high electron affinity bc adding an e creates full valence shell
- alkaline earth metals have low e affinity and donate bc loss of 2 would leave them with full valence
- halogens and alkaline are a good pair for ionic bonding but they dont share electrons equally
lithium and sodium have similar chemical properties and form ionic bonds with cloride. Why are they similar?
they are in the same group with same valence configuration which affects their bonding
- pos charge doesnt affect bonding ( most metals have pos charged ions)
- not related to atomic weight
why are carbon and silicon similar?
as you go to bottom
electron shells increase but valence is the same so electron shells provide shielding between positive nucleus and outermost electrons =-> decrease electrostatic attraction and increases atomic radius
silicon is further down and increases atomic radius as extra electron shell is there
Which has greatest electronegativity of all?
Electronegativity increases from bottom to top in groups, and increases from left to right across periods. Thus, fluorine is the most electronegative element, while francium is one of the least electronegative.
F then followed by O, then N and Cl.
ionization energy contributes to chemical reactivity – how does ionization energy rank from low to highest
increases ionization needed across the table and going up the row
first ionization Li < first ionization of Be < second ionization energy of Be
Li is left of Be and needs less energy
generally greater energy for second ionization energy compared to first
antimony is used in medicines for antiparasites– what type of element is it
antimony (Sb) is right, but not too right to be non metal
its a metalloid
why are metals used for conducting electricity according to periodic table?
metals have valence electrons that move freely
What is a property of group 2 elements?
They form divalent cations –> valence of +2
A dication is any cation, of general formula X²⁺, formed by the removal of two electrons from a neutral species. Diatomic dications corresponding to stable neutral species often decay quickly into two singly charged particles, due to the loss of electrons in bonding molecular orbitals.
when dissolved in water which ion is most likely to form a complex ion with H20?
Na+, Fe2+, Cl-, S2-
A complex ion has a metal ion at its center with a number of other molecules or ions surrounding it – many ions
Transition metals often form more than one ion – Fe
Transition metals in various oxidation states form many hydration complexes with water
when transition metals form a complex, its solubility within related solvent will increase
none of other metals are transition metals and are not likely to form complexes
valence electrons across group and period
number of valence increases towards right across period as increase atomic number
valence within a column (group) is the same
arsenic mediates toxic effects via inhibiting acetyl coa formation to decrease ATP
arsenic can be replaced with phosphorus– why?
bc arsenic and phosphorus are in the same group 5A, they have similar valence – valence is a determinant of bonding, – elements with similar valence states react similarly
Which has greatest effective nuclear charger?
Cl, Cl-, K, K+
Cl and Cl- have same protons, same Zeff = 7
K has the lowest Zeff because additional inner shells shield valence from nucleus - 19-18 = 1
K+ has higher Zeff bc it has same electron configuration as Cl- (10 non valence) but 2 extra protons 19-10 = 9)
what is the highest energy orbital of elements with valence electrons in n = 3 shell
s orbital, p orbital, d orbital, f orbital
When n = 3 quantum number (size of orbital) the angular quantum number l = 0, 1, 2, (shape of orbital)
3d block has quantum number n = 3
Subshells within an energy shell increase s < p < d < f but no 3f subshell
highest is 3d –> d orbital
https://chemed.chem.purdue.edu/genchem/topicreview/bp/ch6/quantum.html
what do we know about HCL, mag powder, potassium chloride, uranium for causing burns
