working scientifically, chemistry, & physics. [SCIENCE_YEAR102025]

revision term 2 yay

independent variable

what you change

dependent variable

what you measure

controlled

kept the same

hazard

what could go wrong

safety

how to protect yourself

control

what you do to reduce the risk

conservation of mass

atoms are not lost/created in chemical reactions—they are just rearranged

atoms

made of protons (+), neutrons (0/neutral), & electrons (-)

chemical reactions

substances rearrange to form new ones. signs; gas, heat, colour change, percipitate, & light

combustion

burning

corrotion

rusting

decomposition

breaks apart

precipitation

solid forms from 2 liquids

exothermic

heat out (fire)

endothermic

heat in (photosynthesis)

living systems reactions

photosynthesis & respiration are chemical reactions in plants/animals

word equations

write as; reactants → products (e.g., hydrogen + oxygen → water)

balancing equations

use small numbers (subscripts) to balance number of atoms on both sides

reaction rate factors

temperature, surface area, concentration, & catalysts change how fast it goes

ionic

metal + non-metal (electrons transferred)

covalent

non-metals are share electrons

polyatomic ions

ions w/ many atoms (e.g., NO3- nitrate, SO42- sulfate)

distance

how far you go

displacement

how far from where you started (w/ direction)

speed

how fast

velocity

rate of change of an object’s positionover time, including its direction

convert units

convert m/s to kmh; multiply by 3.6 & convert back; divide by 3.6

acceleration

how speed changes over time (formula; (v - u) ÷ t

newton’s laws

1. an object at rest stays at rest, & an object in motion stays in motion unless acted upon by a force

2. the force on an object equals its mass times its acceleration

3. & for every action, there’s an equal & opposite reaction

forces

force make things move. measured in newtons (N)

scalar

a quantity that is only need the magnitude (quantity = distance)

vector

a quantity that is only need magnitude & direction (quantity = displacement)

motion

a change in position; an objects position in its location