Outcome 1 Flashcards
what is an atomic emission spectrum?
by passing the light of an element through a prism it produces an atomic emission spectrum for that element
who is given credit for the periodic table we see today?
dmitri mendeleev
how many elements in the periodic table?
118 known elements
what do elements in the same group and period have in common?
group- similair chemical properties i.e. same number valence of electrons
period- have same number of atomic orbitals
what is the oxidising strength of electrons?
how readily an atom gains electrons
what is the reducing strength of electrons?
how readily an atom loses electrons
how can the trends of atomic size be determined?
going across a period it decreases
going down a group it increases
how can the trends of metallic character be determined?
going across a period it decreases
going down a group it increases
how can the trends of reactivity be determined?
going across a period it decreases
going down a group it increases
how can the trends of electronegativity be determined?
going a period across it increases
going down a group it decreases
how can the trends of oxidising strength be determined?
going across a period it increases
going down a group it decreases
how can the trends of reducing strength be determined?
going across a period it decreases
going down a period it increases
what is ionisation energy?
the energy required to remove an electron from a gaseous atom
how can the trends of ionisation energy be determined?
going across a period it increases
going down a group it decreases
what is an ionic bond?
when two atoms gain or lose electrons to form an ionic lattice held together via electrostatic attraction
what is the structure of an ionic lattice?
- held together via electrostatic attraction
- each cation is surrounded by anions and vise-versa
- the relative size and numbers of ions present determine the ‘actual’ lattice structure
properties of ionic compounds with relation to structure
- usually crystalline solids, due to the 3D patterns of the lattice
- have high melting + boiling points, due to the large amount of energy needed to separate ions
- do not conduct electricity in the solid form, due to the fixed particles
- are hard, due to the strong ionic bonds in the lattice
- often dissolve in water, as water molecules are able to move between ions and free them by disrupting the crystal structure
- are brittle, repulsion between like charges shatters the crystal
- in the molten form ions are able to slide past on another and can therefore conduct electricity
uses of ionic compounds
sodium hydrogen carbonate- an enviro friendly cleaning agent
ammonium nitrate- used to manufacture explosives and fertilisers
nitrate, nitrite + sulfite- used to preserve food
why is copper so widely used?
low melting point and the ease in which it could be extracted from its ore
why has aluminium only recently become popular?
was difficult to extract from its ore despite being extremely abundant
properties of metals
- lustrous (due to the mobile electrons being able to reflect light)
- ductile + malleable (layers of atoms can move past one another without disrupting the force between the cations and delocalized electrons)
- good conductor of heat (the bumping of the electrons transfers heat) + electricity (the movement of the delocalized e- form an electric current)
- often hard
- generally have high density (metallic ions are closely packed within the lattice)
substitutional alloy vs interstitial alloy
s- if the atoms of the metals are about the same size they can replace each other in the metal crystals
i- if they sizes differ greatly the smaller atoms may fit into the spaces between the larger atoms
give 2 examples of alloys and their composition
stainless steel- 73% Fe, 18% Cr, 9% Ni
sterling silver- 92.5% Ag, 7.5% Cu
what is work hardening?
bending or hammering cold metals causes their crystal grains to become smaller therefore bending becomes more difficult
