Groups in the periodic table SC17 + Rate of reaction SC18 + Exo/endo thermic reaction SC19 Flashcards
What is in group 1 on periodic table?
Alkali metals
What are the properties of alkali metals?
all malleable and conduct electricity
relatively low boiling points, soft, easy to cut, very reactive and readily form compunds with non-metals
what is true about alkali metals in air?
easily oxidised and burn brightly in air
What is the order or alkali metals with reactivity increasing (start with least reactive)
Lithium
Sodium
Potassium
Rubidium
Ceasium
Francium
What can be observed of alkali metals?
- atom size inceases
- outermost electron gets further away from the positive nucleus
- electrostatic force between nucleus
- outermost electron gets weaker
- therefore electron is lost easier
how do alkali metals react with water?
- react vigorously lower down the list (explosive)
- form hydrogen + metal hydroxide
- higher up: fizz, move, gass given off
how do alkaline metals react with chlorine gas?
- react more vigorously going down
- metal + chlorine = metal chlorine (white solid)
What is group 7 composed of in the periodic table (what is the group name commonly called)?
Hallogens
What are the hallogens in group 7? give their appearances too (decrease reactivity - start at highest)
Florine (pale yellow)
Chlorine (pale green gas)
Bromine (Orange/brown liquid)
Iodine (grey solid)
Astitine (black solid)
What are the properties of hallogens?
- made up of two atoms
- Simple molecular structure
- Melting + boiling points increase going down
- Reactivity decreases going down
what do hallogens form when making an ionic bond with metal?
metal halide
what happens with halogens in displacement reactions?
more reactive ones always displace less reactive ones
what are the properties of nobel gasses?
- colourless gas
- Non flamable
- Low boiling point
- Dont conduct heat/electricty
- Dont react (inert)
- Boiling point inc as going down group
What is the common name for group 0?
Nobel gasses
What are the nobel gases?
Helium
neon
argon
krypton
Xenon
why are nobel gases non reactive?
full outer shells - cannot take on any more electrons
What factors effect the rate of reaction?
concentration increase
temperature increase
catalyst added
large surface are: volume ratio
pressure increase
what are 2 ways rate of reaction can be measured?
quantity reactants / time
or
quantity of products/ time
how does concentration increase rate of reaction?
increases the amount of particles in a given volume, increases the frequency of collisions between particles leading to more successful collisions
how does temperature increase rate of reaction?
increases the temeprature, increases kinetic energy of particles - increases the frequency of collisions between particles leading to more successful collisions
how does a catalyst increase rate of reaction?
spees up ROR by lowering activation energy by providing an alternative energy pathway, mass of catalyst remains constant so isnt used up
how does large surface area : volume ratio increase ROR?
large surface area: volume ratio, increases the frequency of collisions between particles leading to more successful collisions
How does pressure increase effect ROR?
increases pressure decreases volume and moves the particles closer together, increases the frequency of collisions between particles leading to more successful collisions
how will ROR differ between granules and block of reactant?
granules increase ROR as they are smaller and hence increase surface area : volume ratio
What is the equation used when comparing ROR - what is used to measure CO2? why is CO2 measured?
HCl + CaCO3-> CaCl2 + CO2+ H2O
use gas syringe
CO2 is measured becase more C02 given = quicker ROR
how to calculate rate of reaction at time X?
draw a straight line at an angle through the point - connect in a triangle - use equation:
difference in y axis / difference in x axis = gradient
What is are properties exothermic reaction?
feels … to touch, gives/recieves energy?
- gives off energy to surroundings
- feels hot to touch
- thermometer reading goes up during reaction
- Bonds formed > bonds broken
what are the properties of an endothermic reaction?
- takes in energy from surroundings
- feels cold to touch
- thermometer reading goes down during reaction
- bonds formed < bonds broken
what does a reaction graph look like for an exothermic reaction?
- activation energy needed is small
- Entholopy change in reaction is negative
- products end lower than reactants (less energy)
what does a reaction graph look like for an endothermic reaction?
- lots of activation energy required
- entholopy change is positive
- products finish with more energy than reactants
what is activation energy?
minimum energy required to start a reaction
