C4 - Chemical Patterns
the periodic table
an element = 1 kind of atom the atoms have the same number of protons
group - verticle = number of electrons in the outer shell of atom
peroid - horizontal = number of shells in atom
atroms = no overall charge
nucleus = surroundes by electrons (negative) made up of protons (positive) + neutrons (no charge)
line spectrum =light emitted from flame of an element when heated
lithium - red soduim - yellow potassuim - lilac
electron configuration = how the electrons are arranged around the nucleus
first shell - up to two shells after - up to 8
total mass of products = total mass of reactants
no atoms are lost or made in a chemical reaction
alkali metals - group 1 - 1 electron in outer shell
the reactivity of alkali metals increases down the group, this is because the outer shell gets further away from the nucleus and electrons are more easily lost
alkali metal + water = metal hydroxide + hydrogen
Halogens - group 7 - 7 electrons in the outer shell.
they decrease down the the group, as the outer shell gets further from the nucleus and electrons are less easily gained. a more reactive halogen will displace a less reactive halogen.
at room temperature/pressure: chlorine = green gas. bromine = orange liquid. iodine = dark purple solid.
ions = atoms that have gained or lost electrons, have an overall charge
ionic bonding = transfer of electrons between metal atoms an non metal atoms.
atom loses electrons - positive charged ion. atom gained - negative charged atom.
ionic compound - group 1 + group 7. from crystals as ions are arranged in regular lattice. when crystals melt/dissolve in water they conduct electricity
speed - how fast an object is moving
instantaneous speed - speed of an object at a particular point in time
Velocity - describes an objects speed and direction
the gradient of velocity-time graph = how quickly object increases in speed
steeper the slope - faster the speed is increasing
Forces - occurs when two objects interact with each other
Gravity - force of attraction between all masses
Air resistance - air tries to slow an object down
Reaction of the surface - object is pulled down on to the surface by gravity, surface pushes up on to the object with equal force.
Friction - the force that tries to stop two objects moving as they slide past.
Resultant Force - effect of adding or subtracting forces
size of force arrow = size of force
Direction of force arrow = direction force is acting in
force arrows are always drawn with the tail of the arrow touching the object
Momentum - measure of the motion of an object
collisions - cause changes in momentum
if a change in momentum is spread out over a longer period of time, the resultant force will be smaller.
increasing time of impact - reduces force of impact
kinetic energy - energy of object has because of its movement. depends on mass and velocity or object.