Periodic table Chemical bonding Flashcards
Atomic radii trend down group
- Increases down the group
- The number of filled principal quantum shells increase
- Distance between valence electrons and nucleus increases
- EFOA between them decreases and electron cloud increases
Group 1 metals properties
Chemical
- Highly reactive (store under oil to protect from oxygen and water vapour)
- React explosively with water
- React with non metals to form soluble white ionic compounds
Physical
- Good conductor of heat and electricity
- Low mp
- Low density
- Soft and silvery
Group 1 metals density trend
Density icnreases down the group
Group 1 metals mp/bp trend
Decreases down the group
- Atomic radii increases down the group
- Distance between nucleus and delocalised electrons increases, EFOA between them decreases
- metallic bond is weaker and less energy is needed to overcome the EFOA between cations and sea of delocalised electron
Group 1 metals reactivity trend
Increases down the group
- Atomic radii increase down the group
- EFOA between valence electrons and nucleus decreases
- Less energy needed to remove the valence electron from the atom
- First IE decreases and reactivity increases
Group 1 metals reaction with water
Produce metal hydroxide and hydrogen gas
- Effervescence
- Darting on the surface of water
- The beaker feels warm
Potassium - lilac
Barium - yellow
Calcium - orange
Noble gases properties
Chemical
- monoatomic
- low electronegativity
- inert
Physical
- Low mp/bp
- Colourless and odorless gas at room temp
Transition metals properties
Chemical
- reactive/unreactive
- variable oxidation state
- compounds are catalysts
Physical
- High mp/bp
- High density
- Good conductor of heat/elec
- Soft and silvery (less soft than group I metals)
- Forms coloured compounds
Halogens properties
Physical
- Low mp/bp
- Insulators of electricity
Chemical
- Diatomic
Halogens colours
Fluorine: Pale yellow gas
Chlorine: Greenish-yellow gas
Bromine: Reddish-brown liquid
Iodine: Purple gas, Black solid
Halogens bp/mp trend
Increases down the group
- Molecular mass increases
- Intermolecular forces of attraction increase
- More energy to overcome it
Halogens reactivity trend
Decreases down the group
- The number of filled principal quantum shells increase
- Distance between nucleus and valence electrons increases, EFOA decreases
- Harder to attract another electron to form a X- ion
- Reactivity decreases
Atom, Ion, Molecule definition
The smallest unit of an element that cannot be broken down into anything simpler by chemical means
A charged particle that is formed when a single atom or group of atoms loses or gains electrons
Group of atoms that are covalently bonded
Definition of metallic bond
EFOA between sea of delocalised electrons and metal cations
Structure of metals
GIANT METALLIC STRUCTURE
Closely packed in lattice structure (non directional)
- Metals have low IEs, lose electrons easily to form ions
- When the metals ionise, the valence electrons form a sea of electrons
- Electrons occupy the space around the metal ion and are free to move throughout the metal
- They are delocalised and form an electron cloud d
What affects the strength of the metallic bond
- Size of cation (smaller means less distance between cation and electrons, EFOA increases)
- Charge of cation (charge increase, EFOA increase)
- No. of delocalised electrons (greater EFOA between the highly charged metallic ion and greater no. of electrons)
Physical properties of metals
- High mp/bp
- Except for group 1 and Hg
- got strong EFOA between metal ion and sea of delocalised electrons - Malleable and ductile
- Same size metal ions in a orderly rigid structure, creating slip planes between layers
- When a force is applied, the metal ions can slide over one another without disrupting the metallic bond as the delocalised electrons do not belong to any one cation - Electrical conductivity (solid and molten only)
- delocalised electrons act as mobile charge carriers
What do impurities do
Lower melting point
hence alloys melting point is lower than pure metal (good for soldering)
Purpose of alloys
- Improve appearance
- Lower melting point (eg. soldering)
- Stronger (higher tensile strength, less malleable and ductile)
Electronegativity definition
Measure of its ability to attract electrons in a covalent bond to itself
What are the most electronegative things
F followed by O and N
Ionic bond
EFOA between oppositely charged ions formed as a result of the transfer of 1 or more electrons from one atom to another
What affects ionic bond
- Magnitude of charge (greater charge, stronger EFOA)
- Size of radii (smaller radii, greater charge density, stronger EFOA)
Properties of ionic structure
- Hard but brittle
- when a force is applied, ions with similar charged from neighbouring layers face each other
- experience a repulsive force and splits the crystal - High mp/bp
- strong EFOA between oppositely charged ions - Electrical conductivity (molten and aq)
- in solids, strong EFOA hold ions in fixed positions (can only vibrate in fixed positions, not free to move around)
- no mobile ions to act as mobile charge carriers
- in aq/molten, EFOA has been overcome and ions are free to move about, got mobile charge carriers
- Soluble in water
- Water is a polar solvent, can form ion dipole bonds with both positive and negative charges, splits apart the structure - Insoluble in organic solvent
- Non polar, does not interact with ions in the ionic compound, does not split apart the lattice structure
Covalent bonds
EFOA between shared pairs of electrons and nuclei of both atoms
Why water have higher density than ice
In ice, each water molecule has hydrogen bonds with 4 others in a tetrahedral arrangement (got a lot of empty space between molecules )
when heated and the hydrogen bond is overcome, the molecules are packed closer tgt in the liquid state
hence more dense
Properties of simple molecular structure
- Low mp/bp
- most are liquids/gases at rtp
- weak intermolecular forces between molecules, small amounts of energy needed to overcome - Cannot conduct electricity
- neutral without electrons or ions
- unless it dissociates in water - Insoluble in water, soluble in organic solvent
Diamond and graphite structure
Diamond
- each carbon atom is bonded tetrahedral to 4 other carbon atoms with strong covalent bonds
- network is repeated to form a giant molecule
Graphite
- each carbon atom is bonded to 3 others to form a hexagonal 6-carbon ring structure which are joined tgt to form a 2D flat layer
- weak van der Waals forces hold the layers tgt
Diamond vs graphite properties
High mp/bp for both
- extensive covalent bonds between atoms in the giant structure
- need a lot of energy to overcome
Diamond is hard but graphite is soft and slippery
- strong covalent bonds for diamond but weak intermolecular forces between layers for graphite
Diamond cannot conduct electricity but graphite can
- all valence electrons involved in bonding for diamond, no mobile electrons
- 1 electron per carbon atom is not involved in bonding, is mobile charge carrier
