atomic structure and bonding Flashcards
atoms
atoms are basic and smallest particles that matter is made out of
compound
composed of two or more separate elements
molecule
consists of two or more atoms, can consists of any number of elements (1 or 2 or more), a group of atoms bonded together
isotopes
atoms with the same number of protons but a different number of neutrons
same electron configuration and possess similar chemical properties but have different physical properties
cations
positive ions
anions
negative ions
atomic radius: definition
size of the atom. (the distance from the centre of the nucleus to the boundary of the surrounding cloud of electrons)
atomic radius increases…
⬅️⬇️
atomic radius: ACROSS
decreases along a period as the nuclear charge increases, which lead to the increasing attraction of the electrons bringing them closer to the nucleus as the number of protons increase, hence a smaller atomic radius
atomic radius: DOWN
increases as you go down a group as the number of shells increase, hence having a greater distance between the nucleus and the outer electron shell (greater radius)
1st ionisation energy: definition
minimum amount of energy required to remove the single loosely bound outermost electron from a “gaseous” atom (in gaseous phase)
1st IE: formula
Na(g) + E1 → Na+(g) + e- (electron)
1st IE increases…
➡️⬆️
1st IE: across
ionisation energy increases as you go along a period due to the atom’s increasing nuclear charge and decreasing atomic radius, indicating that there’s a stronger attraction between the electrons and the nucleus, hence needing a higher amount of energy to remove the single loosely bound outermost electron from a “gaseous” atom
1st IE: down
ionisation energy decreases as you go down a group as the number of electron shells increases hence electrons are further from the protons’ force of attraction and less energy is required to remove the loosely bound electron as it is easier to remove.
electronegativity: definition
the atoms attraction for electrons in a bonding situation
electronegativity increases…
➡️⬆️
what elements have the highest values of electronegativity?
general non-metals have the highest values of electronegativity as they gain electrons to form ions, conversely metals have low electronegativity
Fluorine has highest electronegativity followed by O, Cl/N, C/S
electronegativity: across
across a period, values of electronegativity increase. down a group, values of electronegativity gradually decrease
smaller AR, greater attraction for electrons as the valence electrons are closer to the attractive force of protons
electronegativity: down
larger AR, outer shell is further ways from nucleus, hence lower force of attraction of protons, hence lesser attraction for electrons
increase in nuclear charge leads to increase of the shielding effect but it has minimal effect on radius going down a group
shielding
the shielding effect described the decrease in attraction between an electron and the nucleus in any atom due to an increase in number of shells
the inner shells shield the outer electrons from the attractive force of protons, ⬆️shells ⬆️shielding
this ⬇️attraction to protons and ⬇️ ionisation energy
core electrons shield the valence electrons from the full attractive forces of the protons in the nucleus
nuclear charge effect on shielding
increase in nuclear charge leads to increase of the shielding effect but it has minimal effect on radius going down a group