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Cartes-fiches
What is the atomic radius?
the size of an ato from the centre of the nucleus to the outermost energy level
Why does the atomic radius decreases in a period?
going across a period, atoms have the same number of energy levels but more electrons and protons which increases the attraction between the nucleus and the electrons, causing the outer shell/level to be pulled in and thus the radius decreases
Why does the atomic radius increase in a family?
going down a family, each new period represents a new shell added further away from the nucelus, each new energy level increases the radius
What is ionization energy?
energy required (erforderlich) to remove an electron from a neutral atom
the stronger an electron is attracted to the nucleus the greater....
the ionization energy, as radius decreases (increasing electron-proton attractiom), ionization energy increases
What is electronegativity?
the ability of an atom to attract a bonding electron
What is the metallic character?
metals tend to lose electrons, non metals tend to gain electrons, elements with a stronger tendency to lose electrons are considered more metallic
Why bond?
- only noble gas atoms have full outer electrons shell, this is the most stable arrangement
- when atoms react, they either lose, gain or share electrons in a way that allows them to have full outer electrons shells, gaining stability
What types of bonds exist?
- ionic bond
- pure covalent bonds
- polar covalent bonds
When do atoms doing a ionic bond?
They do it when they have extremely different electronegativity.
What is a ionic bond?
the attraction between oppositely charged ions is called an ionic bond.
When do atoms do a pure covalent bond?
They do it when both atoms have high electronegativity, so both atoms want to attract an electron, but neither atom can take electrons from the other atom
What is a covalent bond?
a bond created when to atoms which hold their electrons strongely (non-metals) share a pair of electrons.
What is a pure covalent bond?
if both atoms have very similar electronegativities, electrons are shared equally between atoms creating a bond with no electrical charge
When do atoms do a polar covalent bond?
if both atoms have electronegativities that are significantly different but not different enough to create an ionic bond, electrons are shared unequally between the atoms
What does an unequal sharing mean?
the more electronegative atom pulls the electrons closer, this atom becomes negative
this create a bond with one slightly negative end and one slightely positive end
these negativee and positive poles make a dipole
What is polar covalent?
a covalent bond with a dipole
can a molecule have a polar covalent bond and be non-polar?
yes, it depends on the symmetry
