Chemistry IB SL first test

Elements are primary constitutes of matter and cannot be chemically broken down into-

Elements are primary constitutes of matter and cannot be chemically broken down into-

simpler substances

Elements are pure substance and __ exist naturally, and __ are found on the periodic table

92, 118

Elements can exist as both -

atoms and molecules (think HOFBrINCl)

molecules

two or more atoms chemically bonded together

Compounds exist as-

different elements chemically bonded together in a fixed ratio

POLYATOMIC IONS YOU NEED TO KNOW

OH^1- (hydroxide) NO3^1- HCO3^1- CO3^2- SO4^2- PO4^3- NH4^1+

REMEBER ACIDS IN CHEMISTRY

OKAY

What is differnt to the compounds compared to the individual atoms ?

they contain unique properties inherent to the substance

Think about it: Are compounds also molecules? Or are molecules also compounds? Are they the same?

all compounds are molecules, but not all molecules are compounds like the HOFBrINCl

Mixtures

Contain more than one element or compound in no fixed ratio, NOT CHEMICALLY BONDED so they can be separated by physical methods!

Distinguish between compound and mixture:

1) How is their composition different?

2) How can each be separated?

3) How are each written?

1) compunds are in a fixed ratio while mixtures are not

2) Mixtures can be separated physically while compunds can not because they are chemically bonded

3) H2O + NaCL the whole eqaution is a mixture while H2O and NaCl are the compunds

What are the two types of mixtures

Homogeneous and Heterogeneous

Homogenous mixture

same composition throughout, like if something is dissolved ex: lemonade

Heterogeneous mixture

not the same composition throughout ex:salad

Examples for both Homo and Hetero mixtures with gas, solid, and liquid

Homo gas: Air Hetero gas: Air + smoke

Homo solid: stainless steel Hetero solid: concrete Homo liquid: sugar water Hetero liquid: iron grains in water

Methods for separating a mixture

• Solvation,

• filtration,

• recrystallization,

• evaporation,

• distillation

• chromatography

• Magnetism

solvation

adding solute to a substance to dissolve it

Distillation

used to separate water from alcohol

Recrystallization can be used for what

purifying asprin

Chromatography

A technique used to separate the components

of a mixture based on their relative attractions

involving intermolecular forces to mobile and

stationary phases (separte pigments of a mixture)

How do you solve for the retardation factor

Rf= Dp/ Ds

Dp is the distance by pigment

Ds is the distance by solvent

What is used to separte gaseous mixtures

fractional distillation

how does fractional distillation work

separating differnt things on the temperature they melt or boil at (works by heating/cooling up till the exact substance comes off and continue the process to collect different substance)

Kinetic molecular theory

a model to explain physical properties of matter (solids, liquids, and gases) and changes of state

Gas to liquid is called-

Condensation

liquid to gas is called-

vaporization

liquid to solid

freezing

solid to liquid

melting

Gas to solid

deposition

solid to gas

sublimation

differnce between evaporation and boling

evaporation happens surface level while boling happens throughout (both are called vaporization)

chemical equations must have balanced -

charges and number of atoms

include state symbols

What is the center of the atom composed of

protons and neutrons

What seems to make the center of the atom unstable?

If there is less neutrons than the number of protons than the element will be unstable except for helium and hydrogen, it will also be unstable if the number of neutrons exceeds too far over the number of protons. The more protons an element has, the more room you have to add an excess number of neutrons to the protons that won’t cause the element to be unstable.

The charge of the atom is dependent on-

the number of protons and electrons

What is a rule for making a neutral atom which has no charge?

There must be the same number of electrons as protons.

What is a rule for making a positive ion (cation) which has positive charge?

There has to be less electrons than protons

What is a rule for making a negative ion which has negative charge?

There has to be a greater number of electrons than protons.

Characteristics of the nucleus

positively charged, and dense

relative charge of protons , neutrons, and electrons

+1 0 -1

mass number is -

protons plus neutrons

relative atomic mass

the average of the masses of all isotopes of a particular atom

isotopes

Isotopes are atoms of the same element with different numbers of neutron

atomic number

is the number of protons, always the same

mass number will change because of

Different number of neutrons

KNOW HOW TO FIND RELATIVE ATOMIC MASS

OKAY

KNOW THE NUCLEAR SYMBOL A/Z X

okay A=p+n Z=p

in carbon-12, 12 is A

What determines the identity of an element?

An element’s identity is determined by its number of protons in the atom.

atoms are charged how?

they are neutral

Add a  Add a proton

RRem   Remove a neutron

Remove an electron

Add an electron

If you add a proton the identity of the element changes, and the charge too subsequently.

If you remove a neutron the mass will change of the atom or ion.

If you remove an electron the charge of the atom will change and become a positive ion.

If you add an electron the charge of the atom will also change and become a negative ion.

isotopes have the same ___ properites but differnt ___

chemical because they are still the same element, but differnt physical because the mass is changing

physical property

a characteristic of a substance that can be observed or measured without changing the identity of the substance

Examples of physical properties are -

states of matter at various temperatures, melting and boiling points, mass, volume, density, color, texture, hardness, flexibility, malleability, electrical conductivity, thermal conductivity, specific heat capacity

Chemical property

a property or characteristic of a substance that is observed during a reaction in which thechemical composition or identity of the substance is changed

Examples of chemical properties are -

flammability, toxicity, acidity, reactivity (many types), and heat of combustion

Measurable properties fall into one of two categories which colud be -

Extensive or Intensive properties

Extensive properties

depend on the amount of matter present, for example, the mass of gold

Intensive properties

do not depend on the amount of matter present, for example, the density of gold.

Is heat an extensive or intensive property?

extensive

Is temperature an extensive or intensive property?

intensive

What do the number 4,3,2 and 1 mean on the hazmat diamond

4- fire haxzard, 3-health hazard, 2-reactivty, 1-specific hazard

what does a mass spectrometer do ?

measure the amounts of each type of isotope and will produce a graph

KNOW TO FIND MOLAR MASS BY LOOKING AT MASS SPECTROMETER

OKAY

KNOW HOW TO DETERMINE PERCENT ABUNDANCE FORM THE RELATIVE ATOMIC MASS

OKAY

KNOW HOW TO SKETCH A MASS SPECTRUM DIAGRAM POSSIBLY

OKAY

Do humans see in a continous spectrum or line spectrum

continous

emission line spectra

produced by atoms emitting photons when electrons in excited states return to lower energy levels

KNOW HOW TO DO ELECTRON CONFIGURATION

OKAY

KNOW THE EXCEPTONS FOR ELCTRON CONFIGUATION LIKE W AND FE in groups 6 and 11 of transition metals

OKAY

KNOW HOW TO SKETCH EMISSON SPECTRUM DIAGRAM

OKAY

Condensed electron configuration

uses nobel gases-prior to the element

ex: [Ar] 4s^1 3d^10 = Cu

In all chemical equations, how do we show the Law of Conservation of Mass?

We show the law of Conservation of Mass in chemical equations by balancing the equations.

What do we do to balance a Chemical equation?

To balance a chemical equation, we add coefficients in front of the reactants and products so that there is the same number of elements on each side.

When we balance a Chemical equation, why can we NOT change the subscripts in the equation?

We cannot change the subscripts in the equation because otherwise it will change the substance’s identity.

what are the 4 types of Chemical reactions

displacement (includes single and double), decomposition, synthesis, and combustion

Synthesis reaction

two reactants combine to form a single product

Decomposition

one reactant broke down into two products

Combustion

oxygen present in the reactant, with carbon dioxide and water as the products

dispalcement

single: a reaction in which one element replaces a similar element in a compound A+BC→AC+B

double: occur when parts of two ionic compounds are exchanged, making two new compounds.

electrons converage at what

higher energy levels (converage=gets closer together)

H Electrons falling to n=1 produce -

UV light

H Electrons falling to n=2 produce-

visible light

H Electrons falling to n=3 produce

IR light

absrobtion vs emisson spectra

• Emission is when electrons return to energy levels

• Absorption is when electrons gain energy and jump to higher energy levels

  (Absorbed light is light that isn't seen while emitted light is light that is seen)

  (?absorbtion - cold gas emission - hot gas?)

Color results from -

the movement of electrons

Higher energy relation between wavelength and frequency

shorter distance between wavelengths, higher frequency

Low energy relation between wavelength and frequency

longer distance between wavelengths means lower frequency

know order of light for energy/frequency/wavelength

ok

emission spectra arrows on diagram of energy levels point ___ while absobtion point _____

down, up

what does the emission spectrum provide evidence for

the existence of electrons in discrete energy levels

Know the S D P F blocks

ok

shape of s-orbital

sphere

shape of p-orbital

dumbell

what provides eveidence to support the Bohr model of the hydrogen atom

• the energy of the lines in the emission spectra of atomic hydrogen

• The relative intensity of the different spectral lines in the emission spectrum of atomic hydrogen

  (intensity ir related to the energy)

List the 4d 4p 4s 4f in order of increasing energy

4s, 4p, 4d, 4f

KNOW HOW TO DO ELECTRON CONFIGURATION FOR IONS

OKAY

MIGHT NEED TO KNOW HOW TO DRAW BOHR MODEL

OKAY