Periodicity Flashcards
who credited the periodic table today and how was it structured
ordered it by atomic mass but left gaps where elements didn’t fit Newlands theory
elements now grouped in terms of similar chemical properties
how is the modern periodic table grouped
by proton number
same group has similar properties
periods are rows and columns are group
elements in same period have same number of electron numbers
how is the periodic table grouped into s,p,d and f block
left side s block
middle is d block
right id b block
bottom is f block
what is ionisation energy
minimum amount of energy required to remove 1 mole of electrons from 1 mole of atoms in the gaseous state
how does shielding affect ionisation energy
the more electron shells between positive nucleus and negative electron being removed the less energy is required
how does nuclear charge affect ionisation energy
the more protons in the nucleus the bigger the attraction between nucleus and outer electrons, more energy to remove the electron
ionisation requires energy therefore they are always
endothermic and have a positive value
ionisation energy _____as we go down a group
decreases
why does ionisation energy decrease as we go down a group
atomic radius increases
attractive force is weaker
energy required decreases
shielding increases
ionisation energy ___ as we go across a period
increases
why does ionisation energy increase as we go across a period
increasing number of protons
nuclear attraction increases
shielding is similar
more energy required to remove outermost electron
how does aluminium provide evidence for sub shells
the outermost electron sits in a higher energy sub-shell slightly higher energy sub shell which is further from the nucleus
how is sulphur evidence for electron repulsion in an orbital
phosphorus and sulfur both have outer electrons in the 3p orbital so shielding is the same
removing electron from sulfur involves taking it from an orbital with two electrons
electrons repel each other so less energy needed remove electron from orbital with two electrons than one
what is successive ionisation
when more than one electron is removed from the same atom
what are two examples of giant covalent structures
graphite and diamond
describe the structure of graphite and its features
each carbon bonded three times, 4th electron is delocalised
layers slide as weak forces between layers
delocalised electrons allow conduction of electricity
strong covalent bonds mean high melting point
insoluble
describe the structure and function of diamond and its properties
each carbon bonded four times
tightly packed so can conduct heat
high melting point due to strong covalent bonds
doesn’t conduct electricity
insoluble
what substance is diamond similar to
silicon
what bonding is present in metals
giant metallic lattice
what is the structure and properties of graphene
1 layer of graphite
made up of hexagonal carbon rings
delocalised, free moving electrons which strengthen covalent bonds and allow conduction of electricity
transparent and light
what is the use of graphene
aircraft shells
super computers
smart phone screens
describe metallic bonding and how this gives metals their property
positive metal ions amongst sea of delocalised electrons
electrostatic attraction between positive metal ions and negative delocalised electrons
the more electrons the higher the melting point
good thermal conductors
high melting points
good electrical conductors
insoluble as metallic bonds are strong
how does melting point change across a period
increase as metals have increasing positive charge
increasing number of delocalised electrons
smaller ionic radius so stronger metallic bond
