Final KAP Chem

Density

a measure of hoe toghtly packed a substance's molecules are.
The formula for density is d = M/V, where d is density, M is mass, and V is volume. Density is commonly expressed in units of grams per cubic centimetre.

Mass

is a dimensionless quantity representing the amount of matter in a particle or object. The standard unit of mass in the International System (SI) is the kilogram (kg).

Weight

Measure of the heaviness of an object; the amount anything weighs. physics. the vertical force experienced by a mass as a result of gravitation. It equals the mass of the body multiplied by the acceleration of free fall.

Lenght

The measurement or extent of something from end to end; the greater of two or the greatest of three dimensions of a body

Temperature

the degree or intensity of heat present in a substance or object, especially as expressed according to a comparative scale and shown by a thermometer or perceived by touch.

Precision

Refers to the closseness of REPEATED measurement to EACH OTHER.

Accuaracy

Refers to the closseness of a measurement to the CORRECT or ACCEPTED value.

Sig fig rules

1. Any number that isn’t a zero is always a sig fig.

2. Zeros that are between two non-zero numbers are always sig figs.

3. Leading zeros are not sig figs. They only act as placeholders.

4. Zeros that come at the end of a number are significant only if the number contains a decimal point.

5. For values written in scientific notation, all digits in the coefficient are the sig figs.

Conversion factor

Are ratios that relate two ammounts that are equal

Dimensional analysis

Method of solving mathematical problems requiring unit conversions.

Solution

homogenous mixture of two or more substances in relative amounts that can be varied continuously up to what is called the limit of solubility. The term solution is commonly applied to the liquid state of matter, but solutions of gases and solids are possible.

Chemical change

A change does produce a chemical reaction.
evidences:
- A gas is produced
- Light is produced
- A solid (precipitate) is formed from 2 solutions
- Temperature change ( temp goes up if exothermic or down if endothermic)
- Permanent color change

Chemical property

Property that is observed when the substance undergoes a chemical change (reaction), these properties show how a substance react with other substances.
Evidences:
- A gas is produced
- Light is produced
- A solid (precipitate) is formed from 2 solutions
- Temperature change ( temp goes up if exothermic or down if endothermic)
- Permanent color change

Physical change

When a change does not produce a new substance.
EX: - phase changes
- changes of form
- forming a mixture

Physical property

A characteristic that is observed without changing the chemical makeup of the substance.
EX: extensive and intensice properties.

Intensive physical properties

Does not depend on the ammount of matter present.
EX: Color, Melting point, density,specigic heat

Extensive physical properties

Depends on the amount of matter present.
EX: Mass, volume.

Heterogeneous

Is a mixture that does not look uniform.

Homogeneous

Also caled solutions, are a mixture that looks uniform.

Malleable

Able to be hammered or pressed permanently out of shape without breaking or cracking.

Ductile

is the ability of a metal to undergo tensile stress, ability of a metal to receive permanent deformation without fracturing.

Compound

Substance made from two or more different elements that have been chemically joined.

Mixture

2 or more substances physically combined, can be separated by physical methods.

Solid

- Tightly compacted particles
- No compressibility
- Barely moving/ vibrating in place
- Define shape
-Define volume
- Less energy

Liquid

- Less compact
- No compressibility
- Medium movement
- Indefinite shape ( take shape of the container)
- Definite volume
- Medium energy

Gas

- Loosely Compact
- Compressible
- Fast particles
- Indefinite shape (take shape container)
- Definite volume
. Largest energy

Law of Conservation of mass

States that during a chemical reaction, matter cannot be created or destroyed.
- This means that the original atoms can move around and find new partners.
- All of the original atoms that were in the reactans will be present in the products as well.

Heat

The transfer of kinetic energy from one medium or object to another, or from an energy source to a medium or object. Such energy transfer can occur in three ways: radiation, conduction, and convection.

Kinetic energy

the energy an object has because of its motion

Potential energy

is energy that is stored – or conserved - in an object or substance.

Chemical energy

the energy which is stored in the bonds of chemical compounds (molecules and atoms). It is released in the chemical reaction and mostly produces heat as a by-product, known as an exothermic reaction. Examples of stored chemical energy are biomass, batteries, natural gas, petroleum, and coal

Thermal energy

the energy contained within a system that is responsible for its temperature.

Conduction

the transfer of heat energy through matter from particle to particle (touching). most effective in solids, but it can happen in fluids.

Convection

the transfer of heat energy in a gas or liquid by movement of currents, the heat moves with the liquid

Radiation

transfer of heat energy by electromagnetic waves. the only form of heat transfer that can occur in empty space.
ex: sunlight.

Addition and Substtraction with sig figs.

Round the answer to the same number of decimals that the smallest measurement.
7.7 + 887.973 : 895.7

Multiplication and Division

Round the answer so it has the same number of sig figs.
2.33 + 2 : 4

Quantitative Measurements

have a especific numerical value

Derived Units

combinations of simple units. they are produced by multipliying or dividing simple units.

Percent error

calculation used by scientist use to compare an experimental result with a theoreticel or a accepted value.
formula:

|accepted value - experimental value|
------------------------------------------------------------- x100
accepted value

Making Measurements

Measurements should include all certain digits and one uncertain digit (estimated digit).

Burette

Graduate cylinder

Law of conservation of energy

States that the amount of energy in the universe is constant; energy can be converted from one form to another, but it not created or destroyed.

Specific heat

is the amount of heat it takes to raise the temperature of 1 gram of the substance to 1 celcius. INTENSIVE PROPERTY.
C : q/m x change in temperature.

C: SPECIFIC HEAT
q: heat energy

Exothermic Reactions

Reaction that releases heat. It gives out energy to its surroundings. The energy needed for the reaction to occur is less than the total energy released.

Endothermic reaction

Reactions in which the reactants absorb heat energy from the surroundings to form products. These reactions lower the temperature of their surrounding area, thereby creating a cooling effect.

Proton

Positive charge, located in the nucleous

Electron

Negative charge, located in the electron cloud

Neutron

No charge, located in the nucleous.

Atom

The smallest unit of an element that maintains the chemical properties of that element. during chemical, the atom does not split.

Isotopes

Are two or more forms of the same element that differ only in the number of neutrons. chemically thay react identically.

Average atomic mass

Represents the average mass of all isotopes of an element.

Isotope Notation

Allows us to express the identity or isotope quickly and easily. When shorthand notation is used , it will appear one of four ways.
80: the average atomic mass 35: atomic number

80 80
Bromine Bromine Bromine-80 Br-80
35

Ions

Happens when electrons are lost or gained.
The number of protons is not the same as the number of electrons.

Cations

when they lost electrons, they have a positive charge

Anion

When an atom gained electrons, they have a negative charge.

Daltons theory

• All matter is composed by atoms
• All atoms of one elemt are identical, but different from other elements
• Atoms of one element combine with atoms of another element to form compounds during chemical reactions, and they combine in simple whole number ratios
• Atoms are indivisible

Flaws:
• Not all the atoms of one elemnent are equal because it exist the isotopes
Atoms are divisible into protons, neutrons and Electrons

J.J. Thomson

Discovered the electron thanks to his experiment with the cathode ray tubes
Electrons are present in atoms of all types

Ernest Rutherford

He discovered the nucleous of the atom in his gold foil experiment
• The positive charge nucleous bounce in the positive charge gold foil
• He conclude that there is a massive, dense, positevely-charged structure that was very small, that later on became known as the protons ( he discovered them using alpha particles)
• He determinated that atoms are mostly empty space

Niels Bohr

He stated that electrons follow paths called orbits at a fixed distance from the nuicleous, but now, we know that electrons do not behave this way.

Quantum Mechanical Model

• Electron cloud model
Elctrons exist in regions of space around the nucleous which are called orbitals, the paths of electrons are random and we cant predict them, we can only talk that is more probable that is near the nucleous.

Wilhelm Rontgen

Found that invisible rays were emitted when electrons bobarded the surface of certain materials:

Henri Becquerel

accidentally discovered that phosphorecent uranium salts produced spontaneous emissions that darkened photographic plstes

Marie Curie

○ isolated the components emitting the invisible rays (uranium; defined radioctivity and radiation
○ discovered polonium, radium and Curium
died of plastic anemua resulting from large amounts of exposure.

Radioactivity

the process in which particles give off rays

Radiation

the penetrant rays nd particles emitted by a radioactive source

Radioisotopes

isotopes of atoms with unstable nuclei ( too many or too few neutrons). May of them are radioactive and undergo radioactive decay.

Radioactive decay

a spontaneous process where unstable nuclei naturally break down into smaller elements and emit particles and/or enerfy (radiation) to attain more stable atomic configurations.

Nuclide

an isotope; identified by the number of protons and neutrons in the atoms nucleous.

Transuranium Elements

elements with atomic number 92 or higher, there are very rare in nature, most of them are made in artificial ways, they are unstable and most exist for infinetely small moments and decay into smaller, more stable atoms

Nuclear Fission

is when a large nuclide is bombarded with neutrons resulting in the large splitting into several smaller daughter nuclide. It releases more neutrons and a large quantity of energy.

ex: nuclear weapons

Nuclear Fussion

Forcing 2 nuclei to combine (fuse) into 1 nucleus, this can only happen at extremely high temperatures.
• Nuclear fusion power the stars, including the sun.
• Scientists have not found a way to sustain a beneficial nuclear fusion reaction on eart.
• Modern thermonuclear weapons, such as the hydrogen bomb, use the combination of fusion and fission reactions.

King Henry Dance Before Drinking Chocolate Milk

Kilo K 1000
Hecto h 100
Deca da 10
Base -
Deci d 0.1
Centi c 0.01
Milli m 0.001

halogens

group 17, most reactive non-metals.

Alkali Metals

* Group 1
* Most reactive, never found free
* Reacts with H2O

alkali earth metals

group 2, reactive, never found free on nature.

Transition metals

* groups 3-12
* Metallic elements
* Múltiple oxidation states
* Brightly colores

Metalloids

* They are basically a mixture of both
* Brittle
* semiconductors

Metals

* Ductile (ductil)
* Usually solid
* Malleable
* Good heat conductor
* Lustreous (shiny)
* High melting and boiling point
* Good conductors

Tend to loose electrons. (cations)

non-metals

* Solid liquid and gas
* Poor conductors
* Dull (not shiny)
* Low melting and boiling point.

Tend to gain electrons. (anions)

Mendeleev

organized the periodic table by atomic mass. This allowed him to leave holes for yet undiscovered elements. However, it had limitations with grouping.

Mosely

organized his periodic table by atomic number, which we still use today. This not only allowed for undiscovered elements to be added in, it also provided a clearer organization for the groups and families on the periodic table.

Periods

* Horizontal rows
* 1-7
* Represent the energy levels

Groups

* Vertical columns
* 1-18
* 1,2,13-18, are called representative elements, because for example, all elements in group one have 1 valence electron

Zeffective nuclear charge

 is the overall force the protons is nucleons exert  on the surrounding electrons. In an energy level, electrons are attracted to the nucleons equally, regardless of how many electrons are there, this is influenced by the atomic number and the electron repulsion ( electrons Rea each other)

Shielding

is the addition of te entire energy levels between the proton in the nucleons and the valence shell of the electrons. Regardless of the nuclear charge, entire energy levels worth of electrons greatly increase the distance between nucleons and valence shell, reducing attraction, electrons repeal, further increasing distance.

Atomic radius trend

Atomic radius is the radius of an atom, which is ensured in picometers or angstroms, it is measured indirectaly from the center to center (nucleus of 2 atoms)

First Ionization energy

The energy requires to remove the outermost electron from an atom.

Second ionization energy

The energy required to remove each electron from an atom, increases successively. Removing a core electron requires significantly more energy than valence electrons. Also requires a lot of energy when the element reach the octet configuration, because it does not want to loose electrons

Electronegativity trend

A mesure of atoms ability to pull on another atom electron (EN)

Electronegativity difference ina bond of less of 1.7 indicates ionic bonding, aad more than 1.7 indicates (molecular) covalent bonding.

who discover the proton

Ernest Rutherford

who discovered the neutron

James Chadwick

who discovered the electron

Thomson

diference between the atomic mass and average atomic mass

the key difference between atomic mass and average atomic mass is that the atomic mass is the mass of an atom, whereas the average atomic mass is the mass of an atom of a particular chemical element calculated by considering isotopes of that element.

Alpha particles

* ocuurs in large nuclides
* ejects a He particle
* charge: +2
* can be stopped by a sheet of paper
* more massive

Beta - particles

* decays into a proteon and a high speed electron
* occurs when there are mone neutrons that protons
* charge -1
* less massive
* stopped by aluminum foil, etc

Beta + particles

* decays into a neutron and a high speed positron
* occurs when there are too much protons
* charge +1
* less massive
* stopped by aluminum foil, etc

Gamma rays

* high energy radiation in which no particles are emitted, just energy, resulting in a more stable nuclide.
* no charge
* stopped by lead
* doesnt have any mass

wave properties of light

light can travel through space as waves and particles