Chemistry Semester 1 Review

A student calculates the density of a substance at 1.40 g/mL. The accepted value for the substance is 1.30 g/mL. What is the percent error for the student's measurement? Show your work.

(1.40 - 1.30)/1.30 = 0.0769 sig fig 0.77

convert the following measurements 882mg to g 130km to hm 0.00367daL to cL 0.261dg to kg

0.882g 1300hm 3.67cL 0.000261kg

calculate the following and answer in the correct number of sig figs. 2.45g / 1.875mL 450.2g + 157.35g 2.34x10^3mm times 1.2x10^2mm

1.31 607.6 2.8x10^5

Round to the following number correctly: 134.50 to 3 sig fig 305000 to 2 sig fig 0.003652005 to 1 sig fig

135 310,000 0.004

If a 20.0 g sample of Br-84 decayed into 5.0 g of Br-84 in 14 minutes, what is the half-life of Br-84?

20g first half life to 10g second half life to 5g That is 2 half-lives so 14minutes divided by 2 is 7minutes

# of significant figures in 1040g

3

# of significant figures in 0.04604 L

4

# of significant figures in 0.0067000kg

5

triple bond

A chemical bond formed when atoms share three pairs of electrons

double bond

A covalent bond in which two pairs of electrons are shared between two atoms

What is a chemical bond?

A force holding two or more atoms together because of the sharing or transfer of electrons.

What is a chemical group (family)?

A group or family is the vertical column of elements that have similar properties and the same number of valence electrons in their outer valence shell.

Identify the meaning of A, Z, and X for the chemical symbol

A is the atomic mass units (amu) protons + neutrons Z is the atomic number protons X is the element identity ex: C for carbon, O for oxygen

What is a mole?

A mole refers to the number of particles you have in an atom

What is a chemical period?

A period is the horizontal row of elements that increase in atomic number from left to right.

What is the formula for calculating average atomic mass?

AVG = Mass1 x Percent1 + Mass2 x Percent2 + Mass3 x Percent3....

Volume

Amount of space occupied by an object

Describe how Energy, wavelength and frequency are related to each other in the spectrum.

As energy increases the frequency increases and the wavelength decreases.

Describe how wavelength and frequency are identified for each part of the electromagnetic spectrum. (which part has the higher frequency, which part has the longer wavelength, etc.)

As you move from Radio Waves to Microwaves to Infrared to Visible Light ROYGBIV to Ultraviolet, to X-rays to Gamma Waves the Wavelength gets shorter or closer together, the frequency gets higher, and the energy gets higher. So, Gamma waves have the higher frequency and a shorter wavelength than Radio waves.

Niels Bohr

Bohr model showing that electrons were in energy levels and could absorb photons to elevate them to an excited state or higher energy level.

What do chemists use a mole for?

Chemists use a mole to weigh out amounts of substances so that they know how many atoms of each they have.

Define Dalton's atomic theory. Which are no longer true?

Dalton based his theory on two laws, (LAVOISIERS law of conservation of mass and the law of constant composition).All mater is made of atoms which are indivisible, atoms of the same element are identical, two or more atoms form compounds, when atoms are rearranged, they are called chemical reactions.The discovery of isotopes and subatomic particles changed that all atom are identical and that atoms cannot be divided to smaller parts.

extensive property

Depends on the amount of matter being measured

James Chadwick

Discovered the neutrons in atoms

intensive property

Does not depend on the amount of a substance

3 kinds of matter

Element, Compound, Mixture

Identify and define the two types of nuclear reactions. What are the advantages and disadvantageof fission reactions vs fusion reactions?

Fission splits a large atom into 2 or more smaller atoms, not necessarily in half. Advantages - cleaner energy, mass amount of energy, less greenhouse gasses Disadvantages - High risk of radiation, Volatile, Radioactive contamination Fusion combines 2 smaller or lighter atoms into a larger one. Advantages - No harmful waste, relatively inexpensive, low risk, not a greenhouse gas Disadvantages - Almost the same amount of energy is needed to make it, infrastructure is expensive, effects of increase Helium is not known, high levels of heat.

Ernest Rutherford

Gold foil experiment showing that the atom was mostly empty space surrounding a tiny nucleus.

examples of chemical properties

Heat of combustion, Chemical stability (Hydrolysis, Oxidation), Flammability, Oxidation state.

electron affinity

Increases from bottom to top and from left to right

electronegativity

Increases from bottom to top and from left to right

valence electrons

Increases from left to right

atomic radius

Increases from top to bottom and from right to left

Define the 3 types of chemical bonds.

Ionic (transfer of electrons), Covalent (sharing of electrons), Metallic (sharing of delocalized electrons)

Define isotope, ion, cation, and anion.

Isotope - an atom with the same number of protons but different number of neutrons. Ion - an atom with a different number of electrons from the number of protons. Cation - an atom that is an ion which has lost an electron(s) and has become positively charged as a result. Anion - an atom that is an ion which has gained an electron (s) and has become negatively charged as a result.

Who created the modern periodic table? Describe how it is arranged

Mendeleev created the modern periodic table of elements arranged by the atomic mass of chemical elements. Mosley adapted that to arrange the elements by increasing atomic number which is used today.

the 3 basic types of elements

Metals, non metals and metalloids

What 3 major additions to the periodic table were added since its original creation?

Noble Gasses, Lanthanides, Actinides

How do noble gases differ from other elements?

Noble gasses are not reactive and tend to not combine with other elements

Define Nuclear Chemistry.

Nuclear chemistry is the study of the chemical reactions that involve the nucleus of an atom.

identify and define the steps of the scientific method.

Observing, collecting data; Form Hypothesis ask a question; Testing experiment collect data; Theorizing information

What is an electron orbital?

Orbitals are predictions of the location of electrons depending on which orbital they occupy.

How do you identify if a substance undergoes a physical change or a chemical change?

Physical change is in the appearance like water to steamChemical change is when a new substance is formed like Hydrogen and Oxygen forming into water.

Identify the number of protons, neutrons, and electrons for each of the following: bromine-80 chlorine-37 lithium-3 with a 1+ charge oxygen-15 with a 2- charge

Protons 35, Neutrons 45, Electrons 35 Protons 17, Neutrons 20, Electrons 17 Protons 3, Neutrons 0, Electrons 2 Protons 8, Neutrons 7, Electrons 10

Where are the protons, neutrons, and electrons located in an atom?

Protons and Neutrons are in the nucleus of an atom.Electrons are located outside and surrounding the nucleus of an atom.

How does a pure substance differ from a mixture?

Pure substances contain only one type of particle for example lead, aluminum, gold, and silvercan be a compound such as water which combined in a fixed proportion.A mixture has more than one different component for example saltwater has NaCl and H2Owhich individually are pure substances.

What are the parts of the electromagnetic spectrum in order from lowest energy to highest energy?

Radio Waves, Microwaves, Infrared, Visible Light ROYGBIV, Ultraviolet, X-rays, Gamma Waves

Identify the number of paths for each of the different orbital shapes, and the total number of electrons that each orbital can hold

S = 2, P = 6, D = 10, F = 14, G =18

What are the different shapes of electron energy level orbitals?

S orbitals are spheres or round. P orbitals are dumbbell shaped D orbitals are a cloverleaf shape, double dumbbell F orbitals are 2 cloverleafs attached at the middle

Define the states of matter?

Solid: composed of tightly packed particles that do not move around and retain its shape Liquid: loosely packed particles will take the form of the container it is in Gas: particles are so loosely packed they have no shape, can be compressed.

Describe the Bohr model of the atom and its electron activity.

The Bohr model shows the nucleus of the atom in the center with the electron orbital around it in increasing circular energy levels or shells around it and shows the electrons in their perspective states. They can move from one shell to another depending on weather they are in an excited state (move out) or a ground state (move in).

Describe how you determine the type of bond that will form between any two atoms.

The Electronegativity of an atom will help to determine the type of bond. If there is a difference in electronegativity greater than 1.7 the bond will be ionic, If the difference in electronegativity is between 0.4 and 1.69 it is polar covalent. Less than 0.4 the bond is non-polar covalent.

atomic mass

The combined number Protons and Neutrons in the nucleus of an atom

What is electron configuration for an atom?

The electron configuration shows the location of all of the electrons in an atom

Atomic Number

The number of protons found in an atom that gives the atom its identity.

Define the photoelectric effect.

The photoelectric effect is when light in the form of electromagnetic radiation hits a substance and electrons are ejected.

Define Chemistry

The realm of science that studies the properties, composition, and the structure of elements and compounds. How they change and the exchange of energy when the changes happen.

What is the numerical value of a mole?

The value of a mole is 6.022x10^23 also know as Avogadro's number

Werner Heisenberg

Uncertainty principle the precise position of a particle has limits

single bond

a covalent bond in which two atoms share one pair of electrons

How do the number of protons and electrons relate to each other:

a. in a normal atom? The number is the same. b. in an isotope?The number is the same. c. in a cation?Less electrons than protons d. in an anion?More electrons than protons.

group 1

alkali metals

group 2

alkaline earth metals

Physical property

can be observed without changing the chemical nature of the substance

JJ Thomson

cathode ray tube experiment showing that all atoms contain negatively charged subatomic particles or electrons (plum pudding model of an atom)

examples of physical properties

color, density, volume, mass, boiling point, melting point

Metals (definition)

good conductors of heat and electric current, High Luster, ductile, and malleable.

group 17

hallogens

heterogeneous mixture

has no uniform composition

homogeneous mixture

has uniform composition

Metalloids

have properties of both metals and nonmetals can be controlled by changing the conditions they are in like temperature and pressure

electron cloud

he area around the nucleus of an atom that contains the negatively charged electrons.

What is the order that orbitals are filled in?

he orbitals are filled in the order or 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f14 5d10... The s-orbital fills first, The p-orbital fills second, The d orbital fills third, The f-orbital fills fourth.

Accuracy

how close measurements are to a value (not together but close to the bullseye) Precise and Accurate (all together inside the bullseye)

precision

how close measurements are to each other (all together outside of the bullseye)

ionization energy

increases from bottom to top and from left to right

Identify the 2 things that define matter.

mass and volume

chemical property

measured by chancing a substances chemical structure

electron

negatively charged particle found in a cloud around the nucleus of an atom

neutron

neutrally charged particle in the nucleus of an atom

group 18

noble gasses

Dmitri Mendeleev

periodic table placing elements in order of atomic weights

What are the two general types of properties?

physical and chemical

nonmetals (definition)

poor conductors of heat and electric current, usually gasses at room temperature, some are solids like sulfur and phosphorous.

proton

positively charged particle in the nucleus of an atom

Mass

the amount of matter in an object

What is half-life?

the amount of time it takes for half of an element to decay into another element.

nucleus

the center of the atom that contains the positively charged protons and the neutrally charged neutrons.

groups 3-12

transition metals