chemistry - FIRE :)

what are the necessary ingredients for fire

what are the necessary ingredients for fire

heat, oxygen GAS (oxygen 2), and fuel

what is fire made of

not a stuff but a chemical reaction!

what causes different colors in fire

electrons jump energy levels and emit light depending on how far they fall, temperature of the fire

why does water put out fires

water absorbs heat which blocks the fuel from getting the oxygen it needs to sustain itself

can smoke burn

yes weirdly

describe the changes wax undergoes as a candle burns

physically, wax melts then boils

chemically, wax burns and interacts with oxygen

how is burning something different from heating something?

burning something: object uses its own energy to produce heat

heating something: object gets energy from outside source

can all substances change into solid, liquid, and gas form

yes…ish. some have to break down into smaller particles before they change phase

hotter means particles are moving…

faster

as substances change solid to gas, density usually…

decreases. an exception is H20

intermolecular force

force that draws particles towards one another

conservation of motion

the idea that particles transfer motion to each other on collisions

what types of motion does each state have?

solid- vibrational

liquid- rotational, vibrational

gas- translational, rotational, vibrational

explain the relationship between kinetic energy and intermolecular forces

kinetic energy increases from solids to gasses. as this happens, intermolecular forces become less effective at holding the particles together

phase diagrams

A-solid

B-gas

C-liquid

D-triple point, where your particles start acting a lil funky and do everything at once (multitasking ally)

E-critical point, after which you get supercritical fluid

3 parts to kinetic molecular theory

1. all matter is made of particles, so everything can be described by particle motion

2. particles are always moving (0 Kelvin is called absolute zero but we don't know if it exists)

3. particle collisions are perfectly elastic, no energy is lost

temperature vs heat

temperature is the average KE of particles in a system

heat is the amt of energy transferred from system to surroundings due to temperature difference

all abt celsius (not the drink sadly)

celsius got water and said “hey, my water boiled. im calling this 100 degrees celcius.” then his water froze and he said “this point is 0 degrees celcius” and then he divided up everything between into hundredths

we use it for measuring

C=K-273.15

kelvin stuff

kelvin literally said “alr this is an absolute scale so we are making it celsius without negatives”

we use it for calculating

K=C+273.15

what happens to things as you heat them

they expand slightly!

why don’t you take temperature with your own hand

you only feel temperature when there is a heat exchange queen

specific heat capacity

amt of energy to heat 1 g of something by 1 degree C

c=J/g degrees C

calculate heat equation

Q=m*c*change in temp

temperature during a phase change

temp cannot change until a phase change is complete (see heating curves)

heat increases phase energy instead of kinetic energy, changes type of motion instead of increasing it

energy bar charts

j look at the photo

octet rule

elements/compounds tend to react in ways that lead to 8 valence electrons

closer to a full shell, more reactive

full shell, inert

describe what mendeleev did

he sorted the periodic table to predict missing elements!

he helped us see elements should be listed on atomic number

new period (or row)→ new energy level

periodic table

• know how many valence electrons each column has

• know what elements are metals, metalloids, and nonmetals

• know the names for some of the columns

• the rows are called periods, elements in the same period are not that similar

• the columns are groups or families, they are similar

metals

• good heat and electricity conductors

• shiny

• ductile (stretched thin)

• malleable (pounded thinly)

nonmetals

• the opposite of metals

• bad conductors

• brittle and break easily

• dull just like making these flashcards tbh

metalloids

• mix of both metals and nonmetals

• can be shiny or dull

• goodish conductors but not great

• sorta ductile and malleable

• basically manchild of metals and nonmetals

B, Si, Ge, As, Sb, Te, Po, At, Ts, Og

alkali metals (column 1)

very reactive because they only need to lose 1 valence electron to explode

alkaline earth metals (column 2)

reactive but not as reactive

transition metals

the metals that vary in valence electrons

halogens (column 17)

very reactive because they only need one electron for a full shell

noble gases (column 8)

inert because they have a full shell

when you burn a candle where does all the mass go lol

it escapes into the surroundings, wax undergoes chem reaction and turns into water+CO2. mass is not destroyed

atomic radius trend

He has the smallest radius, Fr has the largest

electronegativity trend

Fr has the weakest electronegativity, F has the strongest

noble gases are excluded

coulombs law! YOU NEED TO KNOW THIS PLS DON’T FAIL

1. like charges repel opposites attract

2. charge with higher magnitude has more magnetic force

3. weaker force when farther apart

as you go down the periodic table, atomic radius increases because new energy levels are necessarily bigger

greater distance of energy levels means that electronegativity will go down acc to #3

atomic radius decreases as you go across the periodic table because increased protons and electrons lead to greater force (because there is stronger attraction inside) acc to #2

smaller distance means electronegativity will go higher for the same reasons

energy

ability to cause change

energy can’t be destroted/created but it can be transferred or transformed

potential energy (name the four types)

gravitational - gravity

elastic - stored in an object under strain

nuclear- stored in an atom’s nucleus

chemical - stored in attractive force (bonds) bt atoms

kinetic energy (name 5 types)

radiant- light

sound - vibrations in matter

electrical-electrons motion

thermal-vibration of particles

mechanical-moving

t-e-r-m-s (lil acronym for u)

exothermic reaction

energy is lost

condensation, freezing, deposition

less energy going down a phase

FIRE IS EXOTHERMIC

endothermic energy

energy is gained

boiling, evaporation, melting, sublimation

how does fire grow?

fire is exothermic so it releases enough heat to set other things on fire

where does the energy come from to make fire hot?

As new bonds form, chemical (potential) energy is converted into thermal (kinetic) energy

coulombs law again

1. Opposite charges attract and like charges repel.
2. Larger chargers have a greater repulsive/attractive force while smaller charges are weaker.
3. When charges are close together, their repulsive attractive force is stronger and when they are far apart it grows weaker.

heat of fusion

the energy needed for one gram of a solid to melt or one gram of a liquid to freeze

heat of vaporization

the energy needed for one gram of a liquid to vaporize (boil) without a change in pressure

what happens at each point of this image

A-wax melts and vaporizes

B-wax collides with oxygen and forms new molecules through breaking apart

C-CO2 and vapor float away and sometimes smoke or ash is reaction does not finish

combustion

another term for burning, through combustion in fire you get water and carbon dioxide

where is the energy stored in an unlit candle

chemical potential energy is stored in the bonds (attractive forces) between atoms