Elements Of Life Flashcards
What is Avogadro’s constant?
One mile of any substance contains 6.02x10(23) formula units.
What is the mass, mol, mr equation?
Mol x Mr
What is the mole concentration equation?
Vol x Concn
How do you find the percentage composition of a compound?
% of each element =
Ar of element x no. of atoms of element in formula
———————————————x100
Mr of compound
How do you measure the mass of solids?
Revisit
What are the shapes of the S and P orbitals?
S orbital is spherical
P orbital has a figure 8 shape on three axis’ (xyz)
What is true about fusion reactions?
Lighter nuclei always join to give heavier nuclei under conditions of high temperature and pressure.
What are cations?
Positively charged ions
Mostly metals that want to lose e-
What are anions?
Negativity charged ions
Mostly non-metals that want to gain e-
What is ionic bonding?
Bonding between metals and non-metals to form ions (cations or anions) when the overall energy change for the reaction is favourable.
The transferral of e- from metals to non-metals.
Can ionic bonds/molecules/compounds form a giant lattice?
Yes.
The oppositely charged ions attract each other and build up to form a giant lattice.
Three properties of simple molecular structures
- Low melting points
- Do not conduct electricity
- Usually insoluble in water
What is a dative bond and how is it shown?
When both bonding e- come from the same atom.
Shown using an arrow pointing away from the donating atom.
What are the two covalent structures?
- Covalent molecular structures
2. Covalent network structures
What is the difference between ionic and covalent bonding?
Ionic: when metals on the left-hand side of the periodic table combine with non-metals on the right ( ionic compounds are formed)
Covalent: when non-metals on the right- hand side of the periodic table combine with each other ( covalent compounds are formed)
What are covalent molecular structures?
- they consist of individual molecules
- covalent bonds within the molecule are strong whilst bonds between molecules are weak
- the strength of the imf. determines whether the substance is a gas, solid or liquid (@ norm. temp. )
What are some of the properties of covalent molecular structures?
- low m.p and b.p
- doesn’t conduct electricity
- usually insoluble in water unless bonded to a group which does hydrogen bonding
What are covalent network structures?
• consist of repeating lattices of covalently bonded atoms
What are some properties of covalent network structures?
- insoluble (solids)
- high m.p and b.p
- doesn’t conduct electricity
What is Metallic bonding?
When metal armies lose their e- to form a lattice of regularly spaced positive ions.
The outer e- from each atom contribute to a common pool of e- which randomly move throughout the lattice of +ve ions.
The e- don’t belong to any specific atom therefore are delocalised.
What is a metallic bond?
The attraction of +ve charged ions in the metal to the -be charged delocalised e-
The strength of metallic bonding depends on the no. of e- per atom available for delocalisation
What are some properties of metallic bonding?
- high m.p
- insoluble in water
- conducts electricity when solid or liquid
Does density increase or decrease across a period?
- it increases
- elements with high densities contain heavy particles which are closely packed together so that they occupy a relatively small volume.
- in period 2 the density increases then falls at boron
- in period 3 the density increases then falls at aluminium
Does the m.p and b.p increase or decrease across a period?
- increases
- when an element is melted then boiled, the bonds between their particles must be overcome.
- the strength of these bonds influence whether an element has a high or low m.p or b.p
- in period 3 it stops at silicon
- no. of protons in nucleus increase therefore electrons are pulled in closer (mostly for metals)
