Science EOY Y8 1st 15 minutes

Elements, Compounds and mixtures:

Atom - smallest particle of a chemical element that can exist

Element - substance made up of only 1 atom

Compound - substance made up of at least 2 different types of atom that are chemically bonded together.

Mixture - substance made up of at least 2 different elements or compounds that aren`t chemically bonded together

Molecules - at least 2 atoms chemically bonded together

e.g. water → hydrogen + oxygen

This requires electrolysis

start if the name of compound is metal (if present)

end of compound, if there are 2 elements then it ends with -ide

if there are 2 elements and oxygen it ends with -ate

e.g. NaCl - Na = metal Cl = 2 elements, sodium chloride

Cu = copper

Na = sodium

H = hydrogen

C = carbon

O = oxygen

Mg = magnesium

K = potassium

Br = bromine

In the air, there is 78% nitrogen (N2) , oxygen (o2) 21% used for , 0.9% argon (Ar) , Carbon dioxide 0.04 percent (CO2)

Further Forces:

speed = distance / time

distance - measured in metres (m)

speed - measured in (m/s)

time - measured in seconds (s)

speed is scalar quantity - scalar quantity has no direction

velocity is a vector quantity - vector quantities has a speed and certain direction

speed can remain constant while changing but when object changes direction, velocity changes. a change of velocity is called an acceleration

Acceleration is - speeding up, slowing down, changing direction

Acceleration = change in velocity / time

a = (triangle)

v = find velocity

u = starting velocity

unit is m/s2 = metres per second per second

v = v/t

Newtons 1st law = an object will remain at rest or move at a constant velocity unless acted upon by a resultant force

for graphs = y axis is dependent variable, x axis is independent variable

Newtons 2nd law = acceleration of an object is directly proportional to the resultant force acting upon it and inversely proportional to its mass, e.g. double the force = double the acceleration

force = mass x acceleration, is (n) = (kg) x (m/s2)

air resistance is caused by collisions between air particles and an object.

air resistance acts in the opposite direction to motion, faster an object moves, more air resistance

streamlining is changing a shape that pushes air resistance aside, reducing the air resistance. water resistance acts in the same way, water is dense so water resistance is larger than air resistance

As an object falls through a fluid it accelerates downwards/

as it accelerates air resistance increases. When air resistance is large enough to balance the weight the speed is constant. This is terminal velocity.

force/area = pressure

pressure id how much force is put on an object per unit of area. increases the force increases the pressure. decreasing the area increases the pressure.