Chem 1010 Chapter 2

Front 1

All kinds of matter can be divided into 1 of 2 categories

Back 1

Pure substances and mixtures

Front 2

Pure substance

Back 2

Matter that always has a definite and constant composition. A pure substance is, therefore, a single uncontaminated type of matter.

Front 3

Since the composition of a pure Substance is definite and constant, it will have what?

Back 3

Constant physical and chemical properties. The constant physical and chemical properties are unique to the pure substance.

Front 4

Since pure substances have their own set of unique physical and chemical properties, unknown substances can be identified by observing their properties.

Back 4

True

Front 5

The difference between substance and pure substance is important to note. The word substance is a general term used to denote any variety of matter. A pure substance is matter that contains only one substance.

Back 5

True

Front 6

There are 2 kinds of pure substances

Back 6

Elements and compounds

Front 7

Element

Back 7

A pure substance that cannot be chemically separated into simpler substances. Thus, an element cannot be broken down into Simpler substances.

Front 8

Atom

Back 8

An atom is the smallest unit of an element which still has all the characteristics of the element. Therefore, an element cannot be divided into particles smaller than an atom and still be an element.

Front 9

The ultimate limit of subdivision of matter is what?

Back 9

An Atom

Front 10

Since helium is an element it has all the same kind of atoms And cannot be broken down into simpler substances.

Back 10

True

Front 11

If a pure substance is not an element then it is a compound.

Back 11

A compound is a chemical combination of 2 or more different elements. Therefore, a Chemical compound contains more than one element. The elements which make up compounds are chemically combined together.

Front 12

For the same compound, the elements always combine in the same ratio.

Back 12

True. Therefore, a compound always has the same or a definite composition.

Front 13

When 2 or more elements are chemically combined they form a molecule.

Back 13

Therefore, molecules of compounds are chemical combinations of two or more elements.

Front 14

A molecule is the smallest unit of a compound which still has all the characteristics of the compound.

Back 14

True, A compound cannot be divided smaller than a molecule and still be the same compound.

Front 15

Table salt is a common compound used everyday when eating. The table salt is made up of the element sodium and the element chlorine.

Back 15

True

Front 16

Compounds always have properties that are different from those of the elements used to make them.

Back 16

True, Table salt is made of sodium and chlorine. Table salt is a solid with a high melting point and a salty taste. Sodium is a very reactive metal that Burns in water and has a relatively low melting point. Chlorine is an extremely poisonous gas.

Front 17

Molecules of compounds cannot be broken down into their elements except by chemical methods.

Back 17

True. Therefore, chemically breaking down a compound changes the compound into a new substance.

Front 18

Elements are made up of atoms and compounds are made up of molecules.

Back 18

True. Therefore, the smallest particle of an element is an atom, and the smallest particle of a compound is a molecule. A Compound is made up of 2 or more elements, molecules.

Front 19

Both elements and compounds are pure substances.

Back 19

True

Front 20

Pure substances have a fixed composition which cannot vary.

Back 20

True

Front 21

Compounds can be broken down into their elements by chemical means

Back 21

True

Front 22

Compounds, but not elements, can have a variable composition.

Back 22

False

Front 23

If a substance is not a pure substance then it is a what?

Back 23

Mixture

Front 24

Mixture

Back 24

A physical combination of 2 or more pure substances. The chemical identity of the pure substance in a mixture does not change because they are physically rather than chemically combined.

Front 25

Mixtures are a physical Combination of 2 or more pure substances. The substance in a mixture are not chemically combined. The pure substances in the mixture keep their own identities and most of their physical properties.

Back 25

True. Consider a mixture of salt and pepper. Close examination of this mixture will show particles of pure salt and pure pepper.

Front 26

The substance in a mixture can be present in any amount.

Back 26

It's true. For example, assault and pepper mixture can be 1/3 salt and 2/3 pepper, or 1/2 salt and 1/2 pepper. Therefore, mixtures are characterised as having variable compositions.

Front 27

Because the substance in a mixture retained their original properties, they can be separated by physical means.

Back 27

True. Consider a mixture of iron powder and sugar. Iron is black and sugar is white. Iron is magnetic and sugar is not. Sugar is soluble in water and iron is not. Therefore, iron and sugar can be separated by simple physical means.

Front 28

In theory, physical separation is possible for the components of any mixture. In practice, however, physical separation is sometimes very difficult.

Back 28

It's true. Consider an uncooked pizza. It has many different components, but it would be difficult to pull all those components apart.

Front 29

Mixtures are classified according to how well mixed they are. A mixture can be either heterogeneous or homogeneous Is based on the visual recognition of its components.

Back 29

Heterogeneous, contains visibly different parts or phases. Homogeneous, contains only one phase which has uniform properties.

Front 30

A heterogeneous mixture is the least mixed of mixtures. The different substances are large enough to be seen.

Back 30

True. Granite and concrete are examples of heterogeneous mixtures. Granite contains several different minerals. Some of the minerals are very light coloured while others are nearly black. Concrete contains many different sized rocks surrounded by a fine mixture of cement.

Front 31

Not all heterogeneous mixtures contain solid particles.

Back 31

It's true. Mud is a mixture of soil and water which contain 2 phases, solid and liquid. The phases in a heterogeneous mixture may be different. Therefore, heterogenous mixtures have different substances and can have different phases.

Front 32

Heterogeneous mixtures may have different phases, solid, liquid, and gas.

Back 32

True. For example, oil and vinegar make up a liquid heterogeneous mixture. When they are shaken together, large drops of oil spread throughout the vinegar.

Front 33

Homogeneous mixture

Back 33

A homogeneous mixture is well mixed. The substances which make up the mixture cannot be seen even with a microscope. Therefore, homogeneous mixtures contain only one phase which has uniform properties through it.

Front 34

Homogeneous mixtures of all 3 phases or States of matter, solid, liquid, and gas, are common.

Back 34

Brass is a solid homogeneous mixture of copper and zinc. Rubbing alcohol is a liquid homogeneous mixture of isopropil alcohol and water. Air is a gaseous homogeneous mixture of oxygen, nitrogen, and other gases.

Front 35

Homogeneous mixtures are usually called what?

Back 35

Is solutions. A solution is formed when one substance dissolves in another. Salt water is a solution and is, therefore, a Homogeneous mixture.

Front 36

What is another important property of solutions?

Back 36

The substances are evenly spread out. All parts of a solution must be identical for the mixture to be homogeneous.

Front 37

Substances in a solution May change in physical appearance when they dissolve, however, the substance does not change chemically.

Back 37

True. The sugar in sugar water is no longer white and solid, but the same particles of sugar are present Before & After mixing. Therefore, the substance can change in its physical composition, but the chemical composition does not change.

Front 38

Give an example of one substance present, but 2 phases are present?

Back 38

This type of matter would be ice cubes floating in water.

Front 39

Both homogeneous mixtures and heterogeneous mixtures can be separated into simpler substances by physical means.

Back 39

True

Front 40

In some cases, it is difficult to correctly classify matter.

Back 40

Take for example blood. Without knowing the composition and properties of blood it appears to be a homogeneous substance. However, because blood clots Are made up of several different types of Substances distinctly different from each other with the aid of a microscope, it is actually a heterogeneous mixture.

Front 41

Elements are the simplest of pure substances.

Back 41

True. They cannot be changed into simpler substances by physical or chemical processes. An example of this is the element helium used to fill birthday balloons, iron, gold, copper, and tin were recognised as pure substances long before the modern term element was developed.

Front 42

Each element has a unique name.

Back 42

It's true. Element names have been chosen for many different reasons. For instance, the name of the country where the element was 1st bound, the name of the person who discovered the element, for specific properties of the element, after the name of a planet, or after Greek or Latin words.

Front 43

Elements are represented by what?

Back 43

Chemical symbols. The chemical symbol is an abbreviation for the name of the element. The symbols and names of the more common elements are in bold letters. Learning the names and symbols of the more common elements is a key to having a successful experience in chemistry.

Front 44

Each element has a name and a chemical symbol.

Back 44

True

Front 45

Each chemical symbol consists of 1 or 2 letters.

Back 45

True. These letters are usually taken from the element's name or its Latin name.

Front 46

Each chemical symbol consists of 1 or 2 letters. The 1st letter of the symbol is always capitalised. When 2 letters are used in the symbol the 2nd letter is always lower case.

Back 46

True

Front 47

Elements and their symbols

Back 47

Hydrogen, H, Helium, He, Lithium, Li, Beryllium, Be, Boron, B, Carbon, C, Nitrogen, N, Oxygen, O, Fluorine, F, Neon, Ne, Sodium, Na, Magnesium, Mg, Aluminum, Al, Silicon, Si, Phosphorus, P, Sulfur, S, Chlorine, Cl, Argon, Ar, Potassium, K, Calcium, Ca, Scandium, Sc, Titanium, Ti, Vanadium, V, Chromium, Cr, Manganese, Mn, Iron, Fe, Cobalt, Co, Nickel, Ni, Copper, Cu, Zinc, Zn, Gallium, Ga, Germanium, Ge, Arsenic, As, Selenium, Se, Bromine, Br, Krypton, Kr, Rubidium, Rb, Strontium, Sr, Yttrium, Y, Zirconium, Zr, Niobium, Nb, Molybdenum, Mo, Technetium, Tc, Ruthenium, Ru, Rhodium, Rh, Palladium, Pd, Silver, Ag, Cadmium, Cd, Indium, In, Tin, Sn, Antimony, Sb, Tellurium, Te, Iodine, I, Xenon, Xe, Cesium, Cs, Barium, Ba, Lanthanum, La, Cerium, Ce, Praseodymium, Pr, Neodymium, Nd, Promethium, Pm, Samarium, Sm, Europium, Eu, Gadolinium, Gd, Terbium, Tb, Dysprosium, Dy, Holmium, Ho, Erbium, Er, Thulium, Tm, Ytterbium, Yb, Lutetium, Lu, Halfnium, Hf, Tantalum, Ta, Tungsten, W, Rhenium, Re, Osmium, Os, Iridium, Ir, Platinum, Pt, Gold, Au, Mercury, Hg, Thallium, Tl, Lead, Pb, Bismuth, Bi, Polonium, Po, Astatine, At, Radon, Rn, Francium, Fr, Radium, Ra, Actinium, Ac, Thorium, Th, Protactinium, Pa, Uranium, U, Neptunium, Np, Plutonium, Pu, Americium, Am, Curium, Cm, Berkelium, Bk, Californium, Cf, Einsteinium, Es, Fermium, Fm, Mendelevium, Md, Nobelium, No, Lawrencium, Lr, Rutherfordium, Rf, Dubnium, Db, Seaborgium, Sg, Bohrium, Bh, Hassium, Hs, Meitnerium, Mt, Darmstadtium, Ds, Roentgenium, Rg, Ununbiium, Uub, blank, Ununquadium, Uuq.

Front 48

Chemists are interested in properties, composition, and changes matter undergoes. A most important piece of information about a compound is it what?

Back 48

Composition. The composition of a compound is given by its chemical formula. Chemical symbols for each element in the compound are used to make up the chemical formula.

Front 49

The number of atoms of each element in the formula are given by numerical subscripts to the right of each chemical symbol in the formula.

Back 49

True. When there is only one atom of an element, the subscript is not given as part of the formula.

Front 50

Carbon dioxide is a compound of the elements of carbon and oxygen. What is its formula?

Back 50

CO2. The formula tells you that every molecule of carbon dioxide is made up of one atom of carbon and 2 atoms of oxygen.

Front 51

Water is a compound of the elements hydrogen and oxygen. What is its formula?

Back 51

H2O. This formula tells you that every molecule of water is made up of 2 atoms of hydrogen and one atom of oxygen.

Front 52

Water is a compound and can be broken down by electrolysis, chemical means, to the elements hydrogen and oxygen. Since water contains twice as many hydrogen atoms as oxygen atoms, what will happen?

Back 52

There will be twice as much hydrogen gas as oxygen gas when water is broken down to its elements.

Front 53

Sulphuric acid has the formula H2SO4, what elements make up a molecule of sulphuric acid?

Back 53

Hydrogen sulphur and oxygen

Front 54

The chemical formula for aspirin is C9H8O4, What are the elements which make up aspirin?

Back 54

Carbon, hydrogen, and oxygen

Front 55

It is necessary to follow the capitalization rules for the element symbols. Making a capitalization error can dramatically alter the meaning of the chemical formula.

Back 55

True CoCl2 and COCl2 Are drastically different compounds. Co Stands for the element cobalt and CO stands for one atom of carbon and 1 atom of oxygen. CoCl2 Is a blue solid and COCl2 Is a highly poisonous colourless gas.

Front 56

Sometimes parentheses are used in chemical Formulas What do these mean?

Back 56

The parenthesis mean that there are multiple groups present in the molecule. the numeric subscript following the parentheses always indicates how many atom groups there are inside the parenthesis.

Front 57

Most elements occur as individual atoms. However, some elements occur as molecules. When an element occurs as a molecule it is still what?

Back 57

An element

Front 58

One of the Important aspects of matter which chemist study is chemical change. A chemical change always produces a different or new substance. A different substance is produced because the atoms are rearranged.

Back 58

True

Front 59

Chemical changes occur by what?

Back 59

Chemical reactions. A chemical reaction always produces at least one new pure substance as a result of a chemical change. For instance, carbon dioxide and water are 2 new substances produced in the chemical change associated with the burning of gasoline.

Front 60

A chemical reaction can be represented by what?

Back 60

A chemical equation. Instead of using words to describe the chemical reaction a chemical equation can be used. These are abbreviations using chemical symbols and formulas to describe a chemical change or reaction.

Front 61

Give an example of a chemical equation

Back 61

When charcoal Burns in a barbecue grill, carbon atoms combine with oxygen molecules to form carbon dioxide molecules. The symbol and formula for the reaction can be described as C + O2= CO2

Front 62

In a chemical equation, the numbers in front of the formulas are called coefficients. Coefficients change the amount of assumptions but not the identity of the substance.

Back 62

True. For example, 2H2 + O2= 2H2O

Front 63

Atoms in chemical reactions can only be rearranged. They can never be created or destroyed. Each side of a chemical equation must contain the same number of atoms of each element. The equation must be balanced.

Back 63

It's true. Coefficients are used to balance a chemical equation. By placing the appropriate number in front of a chemical formula the equation can be balanced. Therfore, 2H2 + O2= 2H2O, It means 2 molecules of hydrogen react with one molecule of oxygen to form 2 molecules of water.

Front 64

Is a coefficient affects the whole molecule while the subscript number only affects the element to its left.

Back 64

True

Front 65

The reactions and the products of a chemical reaction are represented by chemical formulas.

Back 65

True. The reactant formulas, starting materials, are always on the left side of the equation.

Front 66

Is in addition to the essential plus, arrow, and coefficients used in chemical equations, there are several optional symbols used to give more information about the chemical substance. What are these?

Back 66

(S) solid, (l) liquid, (g) gas, (aq) aqueous solution

Front 67

It is important to note that atoms can neither be created nor destroyed. There must be an equal amount of atoms on each side of the equation.

Back 67

True