Atoms & molecules Flashcards
Atomic number (Z)
no of protons (no of electrons)
Atomic mass (A)
no of protons and neutrons
Atomic orbital
The regions of space surrounding the nucleus where there is high possibilities of finding an electrons
Molecular orbital
The region of space surrounding the molecules’ nucleus where may or may find an electrons
Covalent Bond
Non- metal & non- metal sharing electrons to fill the outer shell
Ionic Bond
Non- metal & metal gain or lose electrons to fill their outer shell
Metallic Bond
Bond between metal and metal; lattice structure; seas of electrons; Outer electrons delocalised
Good conduction of electrical when it’s solid but not when it’s liquid as the lattice structure no longer exists
Carbon - Carbon bond
- Single carbon bond (1 sigma)
- Double carbon bond (1 sigma, 1 pi)
- Triple carbon bond (1 sigma, 2 pi)
Matter
Anything that has a mass and take up space
Substance
single, pure form of matter
States of matter
Gas, Liquid, Solid
Mixture and Compounds
Mixtures
- Components can be separated by physical method
- Composition is variable
- properties are related to its component
Compounds
- Components cannot be separated by physical method
- Composition is fixed
- properties are unlike to its component
Physical properties
Characteristics we can observe without changing the identity of the substance e.g. colour, temperature, states of matter, density, hardness
Chemical properties
ability of substance change into another substance
Isotopes
Same element with different atomic mass: having same number of protons and electrons but different number of neutrons
Protons give the atom _________
Identity
Electrons give the atom
personality
Atomic radius
the distance between the nucleus to the valence electrons
Total number of electrons at different sub shells
1st shell - 2
2nd shell - 8
3rd shell - 18
4th shell - 32
No of electrons at different orbitals
s- 2
p - 6
d - 10
f - 14
Each orbitals has how many electrons?
2
The 2 electrons in the same orbital has ______spin
opposite spin
Hierarchy of sub shells
1s >
2s> 2p >
3s > 3p > 4s> 3d > 4p >5s
Periodic table:
Groups
Blocks
Period
Periods: Down the periodic table; Similar properties; valence sub shells
Blocks - last orbital to be filled
Groups - across the periodic table; trend in properties; valence e-
Atomic radius _______ across the period because ?
Attraction between nucleus and outer electrons __________
- Decreased
- Nucleus charge increase; Valence e- added onto the same shell
- Increased
Atomic radius _______ down the groups because ?
Attraction between nucleus and outer electrons __________
- Increased
- More no of sub shells added, valence e- is further from the nucleus with greater shielding
- Decreased
Group 1 has (how many) valence e-
Group 2 has (how many) valence e-
Group 7 has (how many) valence e-
Group 1 - 1 e-
Group 2 - 2 e-
Group 7 - 5 e- (because they have a p valence orbital) (They have 7 outer shell e- , 1 short from the electronic configuration of noble gas)
For Group 1 & 2 elements, reactivity ________ down each group
For Group 7, reactivity ________ down each group
- Increase
- Decrease
Noble gas
Full filled outer shell, s2 p6 electronic configuration
Non reactive
Electro- negativity
Measure of attraction of an atom for the shared e- in the chemical bond. It is related to the ionisation energy
Group 1 & 2 elements are strong _______ agents, they tend to ______
Group 7 elements are strong _______ agents, they tend to ________
- reducing agents/ oxidise
- oxidising agents/ reduce
Transition metal
- d block element
- Metal/ good electricity conductors because of their lattice structure and the sea of e- / Mostly hard, shiny, solid
- Mercury is an exceptional example
Dative bond /Co-ordinate bond
e- pairs donors
Octet Rule
Atoms try to fill its valence shell/ achieve the s2 p6 electronic configuration to become stable
Intramolecular Force (Interactive bond)
- Bonding between molecules: ionic/ metallic/ covalent
- Affects chemical properties
Intermolecular force (Attractive bond)
- Bonding within the molecule: hydrogen/ permanent Dipole Dipole interactions/ Van de Waal’s force
- Affects physical properties
Which elements are most likely to form hydrogen bonding
H (delta +) - O/ F/ N (delta -)
ionisation energy
Ability (Energy needed) for the atom to lost its electrons
Hybridisation
- Overlap of two different energy level of orbitals
- Has the properties of the mixed orbitals
No of orbits at each sub level (s, p, d, f)
s- 1 / p- 3 / d- 5 / f- 7
valency
no of e- in the valence shell
cation
+ve ions; tend to be metals
anion
- ve ions; tends to be non-metals
2 p^6
where to find the element in the periodic table?
2- period
p - block
6 - group within block
polyatomic ion
ion with different element
homonuclear combination
atoms of the same element
What is sigma bond
overlap of two orbitals - head to head > s- s / s - p
Overlap of two s orbitals > s- s
What is pi bond
over lap of p orbitals - side to side > p - p
dipole
uneven distribution of e-
pi bond has more energy than sigma bond. why?
the overlap of orbitals
p orbital e- has more energy than s orbital e-
same repel, opposite attract
True
Like dissolve like
True
If a pair of shared e- is pulled closer to one of the atom. Describe it
Unevenly shared e- = unequal distribution of negative e- charge (e- density)
Triple covalent bond is more reactive and stronger than single bond T/F
False
Triple bond is more reactive and has more energy as in higher e- density BUT NOT stronger
Electronegativity range of values
0 - 0.4 > non- polar covalent (no dipole)
0.4- 1.7 > polar covalent (Dipole) (more polar / less polar)
> 1.7 - ionic
