periodic table Flashcards
group properties
-elements in the same group have the same number of valence electrons, hence have similar chemical properties
period properties
-elements in the same period have the same number of electron shells
periodic trends
down the group,
-number of electron shells increases
-valence electrons are further from the positive nucleus
-electrostatic forces of attraction between valence electrons and the nucleus decreases and the size of electron cloud increase
-hence, the atoms increase in size down the group
across the period,
-nuclear charge increases as number of protons increases
-shielding effect is similar as number of electron shells is the same
-there is greater electrostatic forces of attraction between protons in the nucleus and the valence electrons
-hence, atomic size decreases across the period
physical characteristics of alkali metals
-soft and can be cut by a knife
-low density
-relatively low melting and boiling points, decreases down the group
reaction of alkali metals with water
-lithium reacts quickly with water. floats on water, no flame is seen.
-sodium reacts very quickly with water. darts around the water surface, a yellow flame is seen.
-potassium reacts violently with water. darts around the water surface very quickly, a lilac flame is seen.
-rubidium and caesium have very violent reactions with water, which may result in explosions.
alkali metals reactivity trend
down the group,
-size of atoms increases
-easier to lose valence electrons in larger atoms
-hence, the reactivity increases down the group
physical properties of halogens/ group 17
-low melting and boiling points due to weak intermolecular forces between diatomic molecules
down the group,
-a gas to a liquid to a solid
-colour becomes darker/ more intense
-melting and boiling point increases
displacement reactions of the halogens
-a more reactive halogen displaces a less reactive halogen from its halide in solution
most reactive halogen - fluorine
chlorine
bromine
iodine
least reactive halogen - astatine
properties of noble gases
-low melting and boiling points
-colourless gases at room temperature
-stable electronic configuration, hence they are monatomic elements
uses of noble gases
-helium used in balloons and airships
-neon used in advertising lights
-argon used to create an inert environment in the manufacture of steel, and used in fluorescent tubes and low energy light bulbs
physical properties of transition metals
-high melting and boiling points
-high density
-variable oxidation states
-coloured compounds
alkali metals vs transition metals
-transition metals are denser as they have closed packed structures and relatively small radii. there are more atoms in a fixed volume of transition metal than in alkali metal.
-have higher melting and boiling points, except mercury
uses of transition metals
-platinum used in catalytic converters to remove polluting gases, carbon monoxide and nitrogen oxides, from exhausts
-nickel used as a catalyst in the production of margarine
-iron used as a catalyst in the production of ammonia via the haber process
