periodic table and energy Flashcards
what is periodicity
the repeating pattern of behaviour across a period
how is the periodic table arrnaged
in order of increasing atomic number
elements in the same group have similar _______
chemical properties
what is the definition for first ionisation energy
the energy recquired to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous ions with a 1+ charge
what is meant by atomic radius
the distance between the nucleus and the electron being removed
what is meant by nuclear charge
the number of protons in the nucleus
what is meant by electron shielding
the amount of shells between the nucleus and the electron being removed
what is the trend in ionisation energy across a period
- atomic radius decreases
- electron shielding remains the same
- nuclear charge increases
therefore nuclear attraction increases- more energy is required to remove the outermost electron
what is the trend in ionisation energy down a group
- atomic radius increases
- nuclear charge increases (but this is outweighed)
- electron shielding increases
therefore nuclear attraction decreases, less energy is required to remove the outermost electron.
ionisation energy usually increases across a period, however there is a small decrease between Be and B, explain this.
Be’s outermost electron is in a 2s orbital, B’s outermost electron is in a 2p orbital - which is further away from the nucleus. Therefore B’s outermost electron experiences less nuclear attraction, therefore slightly less energy needs to be put in to remove it.
ionisation energy usually increases across a period, however there is a small decrease between N and O, Explain this.
both N and O have their outermost electron in a 2p orbital. However oxygen has 2 electrons paired up in one 2p orbital. Paired electrons in oxygen repel one another, and therefore less energy is required to remove.
ionisation energy usually increases across a period, however there is a small decrease in two places, where are these places
between Be and B
between N and O
what is metallic bonding
the strong electrostatic attraction between positive metal ions and negative delocalised electrons
what are the 3 properties of metals
- conduct electricity - mobile delocalised electrons
- insoluble in water
- strong metallic bonds cause high melting and boiling points
what can affect the conductivity of metals
the number of delocalised electrons, the more delocalised electrons, the more conductive.
why do successive ionisation energies always increase
- larger ratio of protons to electrons
- atomic radius decreases therefore nuclear attraction increases
what is an ionic bond
electrostatic attraction between positively and negatively charged ions
what are the 4 giant covelant lattice structures
diamond
graphite
graphene
silicon
outline the bonding and properties of diamond
- each carbon atom makes 4 strong covelant bonds to 4 other carbons
- the shape around each carbon is tetrahedral bond angle 109.5
- high melting point - strong covelant bonds
- insoluble in water
- does not conduct electricity- no delocalised electrons, all electrons used in bonding
outline the bonding and properties of graphite
- each carbon makes 3 strong covelant bonds to other carbons
- carbons are arranged in a hexagonal arrangment, trigonal planar shape, bond angle 120
- 4th electron is delocalised
- insoluble
- high melting point - strong covelant bonds WITHIN layers
- soft as weak london forces BETWEEN layers
- can conduct electricity due to delocalised electrons
outline the bonding and properties of graphene
- each carbon makes 3 bonds to another carbon
- shape is trigonal planar 120 bond angle
-single layer of graphite - conducts electricity and heat
- insoluble
- very strong
outline the bonding and properties of silicon
- each silicon atom makes four bonds
- tetrahedral shape bond angle 109.5
- high melting point due to strong covelant bonds between atoms
- insoluble
- does not conduct electricity, all outershell electrons used in bonding
what are some practical uses of silicon
used in transistors, as pure silicon does not conduct electricity it must be mixed with a small amount of impurities.
across periods 2 and 3, list all the elements that create a giant metallic lattice
GROUP 2: Li, Be
GROUP 3: Na, Mg, Al
across periods 2 and 3, list all the elements that form a giant covelant lattice
GROUP 2: B and C
GROUP 3: Si
across periods 2 and 3, list all the elements that form simple molecular lattices
GROUP 2: N2, O2, F2, Ne
GROUP 3: P, S, Cl2, Ar
what affects the metling/boiling point of simple molecular lattices
the number of electrons
london forces increase in strength with an increase in electrons.
what is a covelant bond
the bond formed between atoms that share electrons
