Chemistry Connections 49 pg guide

Question 1

Define: Synthesis Reaction

Answer 1

A chemical reaction in which two or more reactants combine to form a product.

e.g. A + B –> AB

Question 2

Define: Decomposition Reaction

Answer 2

A chemical reaction in which a compound breaks apart into two or more products. Usually needs an outside source of energy to take place.

e.g. AB –> A + B

Question 3

Define: Displacement Reaction (Single Replacement Reaction)

Answer 3

A chemical reaction in which a reactant takes the place of some part of a compound. In doing so, a new compound is made, and a separate product is released.

e.g. A + BC –> AC + B

Question 4

Define: Double Displacement Reaction (Double Replacement Reaction)

Answer 4

A chemical reaction in which two elements of compund reactants AB and CD replace each other. The elements are rearranged to form two or more different compound products (AD and CB).

e.g. AB + CD –> AD + CB

Question 5

What is an Oxidation-reduction Reaction or Redox Reaction?

Answer 5

It is a chemical reaction in which the oxidation number of the atoms change. This change is the result of an atom or group of atoms gaining or losing electrons.

Question 6

What is oxidation?

Answer 6

A chemical reaction that involves an increase in oxidation number. Oxidation results from an atom or group of atoms losing one or more electrons.

Question 7

What is Reduction?

Answer 7

A chemical reation that involves a decrease in oxidation number. Reduction results from an atom or group of atoms gaining electrons.

Question 8

Can oxidation and reduction take place together?

Answer 8

Yes, they always take place togethr. The electrons lost by one element are gained by another element. This equilibrates both sides of hte equation.

Question 9

Define: Combustion

Answer 9

A redox reaction that occurs rapidly and produces energy, usually in the form of heat and light. The burning of fuel is a combustion reaction.

Question 10

Define: Corrosion

Answer 10

A redox reaction that occurs when metal is oxidized, usually in the presence of moist air.

Question 11

What is a chain reaction? How does it work?

Answer 11

A series of chemical reactions in which the products of one reaction initiate further chemical reactions of the same kind until a stable product is formed. A product in the first step becomes a reactant in the second step, and so on.

Question 12

What is the Initiation reaction?

Answer 12

The chemical reaction that starts a chain reaction. The product sets up a sequence of repeated reactions.

Question 13

What are the Propagating reaction?

Answer 13

Reactions that produce products that cause another reaction.

Question 14

What is the Termination of a chain reaction?

Answer 14

The reaction or reactions that consume the substances needed kto continue the reactions. At this point, one or more of the starting materials are exhausted.

Question 15

What are Reversible reactions?

Answer 15

Reactions that can go forward or backward, depending on the conditions of the experiment.

e.g. A + B <–> C + D

Question 16

What is an Equilibrium?

Answer 16

The state of a chemical reaction at which the forward and reverse reactions occur at equal rates. Therefore, the concentrations of the reactants and products does not change when conditions remain the same. However, the concentration of the reactants and products do not have to be equal to each other.

Question 17

What is the difference betwwen exothermic and endothermic reactions?

Answer 17

1. Exothermic: produce/release energy.
2. Endothermic: require/absorb energy.

Question 18

What is the Energy of Activation?

Answer 18

The amount of energy needed to cause a chemical reaction?

Question 19

Define: Catalyst

Answer 19

A substance that allows a chemical reaction to take place at a different rate or under different conditions. During the reaction, the catalyst is not consumed or changed.

Question 20

What are Covalent bonds?

Answer 20

Covalent bonds occur when valence electrons are shared between two nearby atoms.

• Covalent bonds create stable compounds if the sharing of electrons brings about a oble gas configuration for each atom (with eight valence electrons)
• Covalent bond one atom does not actually lose an electron that is gained by another atom. Instead, the atoms share the electrons.
• A single covalent bond contains two electrons
• The bond that forms between the chlorine molecules to make Some chemicals may contain double covalent bonds or triple covalent bonds.
• Single covalent bond (single bond): a covalent bond sharing only one pair of electrons.
• Double covalent bond (double bond): a covalent bond sharing two pairs of electrons.
• Triple covalent bond (triple bond): a covalent bond sharing three pairs of electrons.

Question 21

What is metallic bonding?

Answer 21

Metallic bonding occurs when the atoms in a metal contribute their electrons to a “sea” of shared electrons. This “sea” of electrons spans the entire structure.

• Metallic bonds are collective by nature, so a single metallic bond does not exist.
• In a metal, the valence electrons are shared among all the atoms in the solid.

– The creation of an electron “sea” only occurs if there is nowhere else for the electrons to go.

– Metallic bonds tend to occur when the Coulombic forces attracting the electrons are weak in comparison to the electron energy. This allows the electrons to be easily lost by the atoms. Each metal atom gives up its valence electrons, forming a “sea” of electrons.

• Elements along the left side of the periodic table often form metallic bonds.
• Metallic bonds also form among elements that have high ionization energies. These elements’ atoms do not give up electrons to other substances easily.

– Gold, cadmium, iridium, and platinum are metals with relatively high ionization energies. For example, many atoms of gold will come together to form strong metallic bonds that will not give up electrons to other substances.

• Some metallic elements are actually quite easy to keep in pure form because they are relatively unreactive. These elements include gold, copper, and silver.

Question 22

What are the properties of metal?

Answer 22

• Luster: the ability of a metal to reflect light. This property gives metals a shiny appearance.

– The large number of freely moving electrons in a metal absorb and re-emit light.

• Electrical conductivity: a measure of the rate at which electricity can travel through a material.

– Metals have good electrical conductivity because their electrons can move easily throughout the metal. •

Thermal conductivity: the measure of the rate at which thermal energy can travel through a material.

– Metals also have good thermal conductivity. As heat is applied to a part of the metal, the electrons become excited. When this happens, the electrons travel to the other side of the metal, carrying the energy with them. The electrons are much better at carrying the energy than the nuclei of the atoms.

• Malleability: the ability of a metal to be flattened, shaped, or formed, without breaking, when pressure is applied. This includes the ability of a metal to be hammered into a thin sheet.

– The mobility of electrons allows metal atoms to slide past one another when stress is applied. They do so without experiencing strong repulsive forces that would cause other materials to shatter.

• Ductility: the ability of a metal to be stretched into a thin wire or thread without breaking.

– Like malleability, the mobility of electrons in a metallic bond allows the atoms to slide past one another as the metal is pulled and reshaped.

Question 23

What are contact forces? Examples?

Answer 23

Forces that require touch. e.g. friction, air resistance, and tension.

Question 24

What are non-contact forces? Examples?

Answer 24

Forces that can act on objects at a distance. e.g. gravity and magnetism.

Question 25

Intermolecular force?

Answer 25

Forces acting between molecules.

Question 26

Define Electromagnetivity.

Answer 26

A chemical property that describes a measure of how strongly the nucleus of an atom attracts electrons when bonding with other atoms.

Question 27

What are the types of bonding?

Answer 27

• Ionic bonding is essentially the result of an atom donating an electron to another atom so that they both complete their octets.
• Covalent bonding is the result of atoms that both need electrons, so they share.
• Metallic bonding is the result of collectively shared electrons.

Question 28

What is gravity?

Answer 28

Gravity is the force of attraction between all objects in the universe.

• It is the force that keeps the planets in our solar system within their orbits around the sun.

Question 29

Who dicsovered the concept of gravity?

Answer 29

Sir Isaac Newton was a famous English scientist known for his work in astronomy, physics, mathematics, and chemistry. As a university student, he developed some important ideas, including his theory of gravity.

When Newton observed a falling apple, he wondered why all objects fall to the ground. He concluded that some force pulls objects toward the center of the earth. This force, which he called gravity, acts throughout the universe and pulls all objects toward each other.

He further explained gravity through the following formula for universal gravitation: Fg = G*m₁m₂/r₂ where Fg is the gravitational force, m1 and m2 are the objects’ masses, r is the distance between the two objects, and G is the universal gravitation constant.

Question 30

What is a magnet?

Answer 30

A magnet is an object that creates a strong magnetic field (an area of magnetic force).

• Only certain metals produce a magnetic field, including iron, nickel, and cobalt. All magnets are made of these types of metals, called ferromagnetic metals. Therefore, magnetism is a property of some metals but not all.
• All magnets have two poles, a north pole (N) and a south pole (S).
• Two like magnetic poles will repel each other
• Metals that do not produce a magnetic field will not be attracted to a magnet.
  
  • There are two basic kinds of magnets—permanent and temporary.
  • A permanent magnet keeps a certain level of magnetism for a long time.
  • A temporary magnet acts like a permanent magnet when it is within a strong magnetic field. It will lose its magnetism when the magnetic field is removed.

Question 31

What is magnetism?

Answer 31

Magnetism is a force of attraction or repulsion between magnetic materials. The magnetic forces are exerted all around the magnet but are the strongest at its poles.

The magnetic field of a magnet is illustrated by magnetic field lines. Magnetic field lines spread out from one pole and make a curved path around the magnet to the other pole. These lines do not touch. However, in areas where the lines are closer together, the magnetic force is stronger.

Question 32

What two elements’ electrons occupy only the first energy level.

Answer 32

Hydrogen and Helium.

Question 33

What ancient civilization discovered magnets?

Answer 33

Humans have known about magnetic materials for over 2,000 years. The ancient Greeks discovered a unique type of rock in the city of Magnesia.

These rocks attracted materials containing iron. They would also attract or repel other similar rocks.

These rocks, known as lodestones, are naturally magnetic rocks that contain the mineral magnetite. Magnetite is an iron oxide with the chemical formula Fe₃O₄.

The Chinese found that if a lodestone was allowed to swing freely from a string, one part of the rock would always point in the same direction. It would point toward the North Star. As a result, the Chinese are credited with inventing the magnetic compass.

Question 34

What are isotopes?

Answer 34

Elements tend to exist in more than one form, called isotopes. Isotopes of elements differ in the number of neutrons in their nucleus, so they also differ in their mass numbers.

Extra information to learn:

Carbon-12 is the most common form of carbon. It was adopted in 1961 as the standard for defining all atomic weights.

Carbon-13 is non-radioactive and is frequently used for isotopic labeling studies. These studies follow how a carbon atom goes through specific reactions.

Carbon-14 is used in a process called carbon dating.

– After 5,730 years, half of the nuclei in a sample of a carbon-14 decay. (This period of time is its half-life.)

– Scientists use the predictable decay of carbon-14 to determine the age of organic materials up to 50,000 years old.

– Carbon dating is useful for studying artifacts left behind by ancient cultures.

Question 35

What is the effect of higher or lower electromagnetivity?

Answer 35

Higher electromagnetivity means it has a stronger pull on its electrons. Lower electromagnetivity means it has a lesser pull on its electrons.

Question 36

What is ionization energy?

Answer 36

Ionization energy is the amount of energy needed to remove the outermost electrons from a nuetral atom.

Question 37

What is the general trend of ionization energy on the periodic table?

Answer 37

Within periods it tends to increase from left to right across the periodic table.

Question 38

What are Radioisotopes?

Answer 38

Atoms that are radioactive.

Question 39

What is ionization energy measured in?

Answer 39

It is measured in kilojoules per mol (kJ/mol).

Question 40

Who discovered radioactivity?

Answer 40

HENRI BECQUEREL

In 1896, French physicist Henri Becquerel accidentally discovered radioactivity. He was actually investigating phosphorescence in uranium salts

Question 41

Who discovered that that thorium?

Answer 41

Marie Curie discovered that the element thorium was “radioactive,” a term she created.

Question 42

What are the charecteristics of Polonium? How many isotopes does it have?

Answer 42

Polonium was discovered by Marie and Pierre Curie in 1898. Therefore, the element was named after the country Poland, where Marie Curie was born.

Characteristics:

• Is a very rare natural element, found in extremely small amounts in uranium ores.
• Is mainly used as a source of neutrons, generally by combining it with beryllium.
• Has specialty uses in eliminating static electricity in machinery and removing dust from photographic film.

Polonium has over 25 known isotopes. Its most common isotope, Po-210, has a half-life of only 138 days. The radioactive decay of Po-210 produces a lot of heat (140 watts per gram).

Question 43

How is the atomic radius determined?

Answer 43

By how close one atom is to a neighboring atom. It is half teh distance between the nuclei of two atoms of an elemant. The distance is so small it is usually measured in picometers (10^-12).

Question 44

What are the characteristics of Radium?

Answer 44

Radon comes from the radioactive decay of the element radium.

Characteristics:

• Is radioactive; the isotope with the longest half-life is radon-222 with a half-life of only four days.
• Is a colorless radioactive gas at a normal room temperature of about 70–75 ºF.
• Glows with a yellow color when cooled to its solid state.
• Is emitted naturally, in some regions, from the soil and rocks and can sometimes build up in people’s homes.

Question 45

What is the 3 types of radiation are produced by radioactive decay?

Answer 45

ALPHA (α) RADIATION (Alpha particles): radiation composed of helium-4 nuclei (having a nucleus that is the same as helium with two protons and two neutrons).

• Alpha radiation travels very slowly and only a very short distance through air. It cannot penetrate skin or even a thin sheet of paper. • Alpha particles are not radioactive. After losing their energy, they attract two electrons to become a helium atom.

BETA (β ) RADIATION (Beta particles): radiation composed of electrons, emitted from an unstable nucleus, that are in high velocity.

• Beta radiation can travel several meters through air but is stopped by solid materials.
• Beta particles can penetrate human skin, but clothing often helps to block most beta particles.
• If the release of a beta particle does not get rid of the extra energy in an unstable nucleus, the nucleus will often release the rest of the excess energy in the form of gamma rays.

GAMMA (γ) RADIATION (Gamma rays): radiation composed of high-energy photons in the form of electromagnetic radiation. • Gamma radiation is able to travel many meters in air. It easily penetrates most materials, including several centimeters through human tissue.

• Gamma radiation frequently accompanies the emission of alpha and beta radiation.

Question 46

Who invented the Greiger Counter?

Answer 46

Johannes Wilhelm “Hans” Geiger was a German physicist known for his work on radioactivity. In 1928, with fellow physicist Walther Müller, he developed a device to measure radioactive emissions. The device became known as the Geiger Counter. The two worked to improve the device’s sensitivity, performance, and durability. As a result, they created a tool that is used in laboratories around the world today.

Question 47

What are nuclear reactions?

Answer 47

Nuclear reactions are changes that occur in the structure of atomic nuclei. The energy that results from nuclear reactions is called nuclear energy or atomic energy. Nuclear energy is released from atoms in two different ways: nuclear fission and nuclear fusion.

Question 48

The size of atomic radii tends to ____ from left to right across the periodic table.

The size of atomic radii tends to ____as you move down a group of the periodic table.

Answer 48

• decrease*
• increase*

Question 49

What are charecteristics of Uranium?

Answer 49

Uranium was first identified in pitchblende ore in 1789. It was named after the planet Uranus, which had been discovered around that time.

Characteristics:

• Is the heaviest naturally occurring element on Earth, except for minute traces of neptunium and plutonium.
• Is highly radioactive, toxic, and carcinogenic.
• Has over 16 isotopes, all of which are radioactive.

Question 50

Who first detected uranium?

Answer 50

Uranium’s radioactivity was first detected by Henri Becquerel in 1896.

Today, it is primarily used in nuclear fuels and explosives. Uranium, specifically the isotope uranium-235, is the principle element used in nuclear reactors and in certain types of atomic bombs.

Question 51

What is nuclear fusion?

Answer 51

Nuclear Fusion: a nuclear reaction that occurs when the nuclei of atoms join to make a larger nucleus. Again, energy is given off in this reaction. • Nuclear fusion only occurs under very hot conditions. • The sun and all other stars create heat and light through nuclear fusion. In the sun, hydrogen nuclei fuse to make helium.

Question 52

Who worked on beta decay?

Answer 52

Enrico Fermi was an Italian physicist most noted for his work on beta decay, for the development of the first nuclear reactor, and for his contributions to the development of quantum theory. He worked on the Manhattan Project during World War II to produce the atomic bomb, though he warned of its power. In 1938, Fermi won the Nobel Prize in physics for his work on radioactivity. Element 100 was named after him.

Question 53

What are the charecteristics of plutonium

Answer 53

Plutonium was discovered in 1940 at the University of California at Berkeley. It was named after the dwarf planet Pluto. The element’s discovery, however, was kept classified by the government until 1946.

Characteristics:

• Is a very heavy, silvery metal in pure form.
• Is a rare radioactive element; found in minute amounts (one part per trillion) in uranium ore.
• Used mainly as a fuel for nuclear reactors and nuclear bombs. Plutonium was produced in large quantities in the U.S. during World War II, as part of the Manhattan Project to create the atomic bomb. Over one-third of the energy produced in most nuclear power plants comes from plutonium.

Question 54

What are transuranic or transuranium elements?

Answer 54

The elements above atomic number 92

They do not occur naturally on the earth. Most of these heavier elements have been made by bombarding the element uranium with neutrons or other particles in a cyclotron.