quimica TEST #1 CHAPTER 2

Question 1

The concept of atoms was first proposed by:

____________, a term derived from the Greek word for “___________”.

Later, ____________ and others believed that matter consisted of various combinations of the :

In _______, English schoolteacher, _______ _______, proposed :

Answer 1

Greek philosophers, Leucippus and Democritus, in the fifth century BC.

atomos, a term derived from the Greek word for “indivisible”.

Aristotle; four “elements”—fire, earth, air, and water.

In 1807, English schoolteacher, John Dalton, proposed his atomic theory.

Question 2

Dalton’s atomic theory can be summarized in:

1)

2)

3)

4)

5)

Answer 2

five postulates

1)Matter is composed of exceedingly small particles called atoms. An atom is the smallest unit of an element that can participate in a chemical change.

2) An element consists of only one type of atom, which has a mass that is characteristic of the element and is the same for all atoms of that element.

3) Atoms of one element differ in properties from atoms of all other elements.

4) A Compound consists of atoms of two or more elements combined in a small, whole-number ratio. In a given compound, the number of atoms of each of its elements are always present in the same ratio.

5) Atoms are neither created nor destroyed during a chemical change, but instead rearrange to yield a different type (s) of matter.

Question 3

dalton’s atomic theory and law of conservation of matter

If atoms are neither created nor destroyed during a chemical change, then….

Answer 3

then the total mass of matter present when matter changes from one type to another will remain constant.

Question 4

dalton’s atomic theory and law of definite proportions

All samples of a pure compound contain the:

Answer 4

same elements in the same proportion by mass.

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Question 5

The law of multiple proportions states that:

For example: compounds containing chlorine and copper.
A green solid contains 0.558 g Cl to 1 g Cu.
A brown solid contains 1.116 g Cl to 1 g Cu.

Answer 5

when two elements react to form more than one compound, a fixed mass of one element will react with masses of the other element in a ratio of small, whole numbers.

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Question 6

In the two centuries since Dalton developed his ideas, scientists have made significant progress in furthering our understanding of atomic theory.

What were atoms composed of?

Was there something smaller than an atom?

Answer 6

leer

Question 7

discovery of electrons

J.J. Thomson’s results:

-The cathode ray particles were:

-These particles are :

-These particles are :

-This cathode ray particle is what we now call an _______ - which is…

Cathode ray tube, invented in _______ by :

In the cathode ray, the beam comes from the cathode and is accelerated past the anode toward a fluorescent scale at the end of the tube. Simultaneous deflections by applied electric and magnetic fields permitted Thomson to calculate the mass-to-charge ratio of the particles composing the cathode ray.

Answer 7

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• much lighter than atoms.

-negatively charged.

-indistinguishable, regardless of the source material.

-This cathode ray particle is what we now call an electron - a negatively charged, subatomic particle with a mass more than one thousand times less than that of an atom.

cathode ray tube, invented in 1897 by Ferdinand Braun.

Question 8

Robert A. Millikan’s ________ Experiment (_____)

Millikan created :

These drops could be:

Millikan was able to determine the:

Millikan’s results:
The charge of an oil drop was always a multiple of a specific charge:

Millikan concluded that ______________ was the charge of a single electron.

Thomson already showed the charge to mass ratio of an electron to be :

Answer 8

Oil Drop, (1909)

microscopic oil droplets, which were electrically charged.

slowed or reversed by an electric field.

charge on individual drops.

ver vid

-1.6 x 10-19 C.
-1.6 x 10-19 C

-1.759 x 1011 C/kg.

Question 9

Thomson suggested that atoms resembled plum pudding, an English dessert consisting of moist cake with embedded raisins (“plums”).

Nagaoka proposed that atoms resembled the planet Saturn, with a ring of electrons surrounding a positive “planet.”

Answer 9

leer

Question 10

discovery of the nucleus

Ernest Rutherford’s ___________ Experiment:
-process:

• α particles are :

-The scattering of these α particles was examined using a _______________ that would glow briefly when hit.

Rutherford’s results:
-The volume occupied by an atom must consist of:

-…………. must be at the center of each atom.

-The _______ contains :

-Negatively charged electrons surround the ________.

-The _______, a …….., subatomic particle is located here

The α particles are deflected only when they collide with or pass close to the much heavier, positively charged gold nucleus. Because the nucleus is very small compared to the size of an atom, very few α particles are deflected. Most pass through the relatively large region occupied by electrons, which are too light to deflect the rapidly moving particles.

Answer 10

Gold Foil Scattering

Aimed a beam of alpha particles (α particles) at a very thin piece of gold foil.

positively charged.

luminescent screen

• a large amount of empty space.

-A small, relatively heavy, positively charged body, the nucleus,

-nucleus, most of the atom’s mass.

-nucleus

-proton, positively charged

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Question 11

menciona todos los experimentos y los cientificos

Answer 11

-J.J. Thomson CATHODE RAY PARTICLES experiment, discovery of electrons

-Robert A. Millikan’s Oil Drop Experiment (1909)

-Nagaoka proposed that atoms resembled the planet Saturn

-Ernest Rutherford’s Gold Foil Scattering Experiment

Question 12

Isotopes are:

(person) . Noble Prize in 1921.

Neutrons are:

Discovered by ______ in _____.
Neutrons are also found in :.

Answer 12

atoms of the same element that differ in mass.

-Frederick Soddy of England

-uncharged, subatomic particles with a mass approximately the same as that of protons.

-James Chadwick in 1932.
-the nucleus

Question 13

The nucleus contains most of :

Protons and neutrons are much heavier than:

Electrons occupy almost all of an atom’s :

Diameter of an atom ~ :

Diameter of a nucleus is 100,000 times smaller ~ :

Answer 13

an atom’s mass

• electrons.

-volume.

-10^-10 m

-10^-15 m

Question 14

Atoms and subatomic particles are very small.

Example: A carbon atom weighs less than 2 x 10^-23 g.

Electrons have a charge of less than 2 x 10-19 C.

Small units are needed.
Atomic mass unit (amu).
1 amu =

Mass of a carbon-12 atom = ____ amu
Mass of a mole of carbon-12 = ___ grams
Fundamental unit of charge (e).
e = ______ C

Answer 14

1.6605 x 10^-24 g.

12 amu

12 grams

1.602 x 10^19 C

Question 15

properties of subatomic particles

Proton
Mass = _____ amu
Charge = ___

Neutron
Mass = ______ amu (slightly heavier than a proton)
Charge = ___

Electron
Mass = _______ amu
Charge = ___

Answer 15

Proton
Mass = 1.0073 amu
Charge = +1

Neutron
Mass = 1.0087 amu (slightly heavier than a proton)
Charge = 0

Electron
Mass = 0.00055 amu
Charge = -1

Question 16

The number of protons in the nucleus of an atom is:

This is the defining trait of an element:

For example, any atom that contains six protons is the element carbon and has the atomic number 6, regardless of how many neutrons or electrons it may have.

Answer 16

its atomic number (Z).

Its value determines the identity of the atom.

Question 17

A neutral atom must contain the same number of :

The number of protons equals the :

Therefore, the atomic number also indicates the:

Answer 17

positive and negative charges.

number of electrons.

number of electrons in a neutral atom.

Question 18

The total number of protons and neutrons in an atom is called its :

The number of neutrons is therefore the :

atomic number (Z) =

mass number (A) =

A – Z =

Answer 18

mass number (A).

difference between the mass number and the atomic number.

= number of protons

= number of protons + number of neutrons

= number of neutrons

Question 19

When the number of protons and electrons are NOT equal, ….

Charge of an atom=

Atoms (and molecules) acquire charge by :

Answer 19

the atom is electrically charged and called an ion.

= number of protons – number of electrons

losing or gaining electrons.

Question 20

An atom that gains one or more electrons will exhibit:

Example: A neutral oxygen atom (Z = 8) has eight electrons, and if it gains two electrons it will become an anion with a 2− charge (8 − 10 = 2−).

An atom that loses one or more electrons will exhibit:

Example: a neutral sodium atom (Z = 11) has 11 electrons. If this atom loses one electron, it will become a cation with a 1+ charge (11 − 10 = 1+).

Answer 20

a negative charge and is called an anion.

a positive charge and is called a cation.

Question 21

A chemical symbol is :

For example, the symbol for mercury is Hg.

Some symbols are derived from …..; others are abbreviations of the name :

Most symbols have __________, but _________ have been used to describe some elements that:

Only the first letter of a chemical symbol is :

Answer 21

an abbreviation that we use to indicate an element or an atom of an element.

the common name of the element; in another language.

one or two letters; three-letter symbols have been used to describe some elements that have atomic numbers greater than 112.

capitalized.

Question 22

The symbol for a specific isotope of any element is written by :

The atomic number is sometimes written as a :

For example, magnesium exists as a mixture of three isotopes.
24^Mg, 25^Mg, and 26^Mg
All isotopes have 12 protons, but the number of neutrons are different.

all elements have the same number of protons but isotopes have different number of neutrons

The symbol for an atom indicates the element via its usual two-letter symbol, the mass number as a __________, the atomic number as a ____________(sometimes omitted), and the charge as a ___________

Answer 22

placing the mass number as a superscript to the left of the element symbol.

subscript to the left of the element symbol.

The symbol for an atom indicates the element via its usual two-letter symbol, the mass number as a left superscript, the atomic number as a left subscript (sometimes omitted), and the charge as a right superscript.

Question 23

Each proton and each neutron has a mass of ~ :

Each ________ weighs far less.

Therefore, the atomic mass of a single atom in amu is approx. equal to its:

However, most elements exist naturally as a mixture of _____

The periodic table lists the weighted, average mass of :

For example, the element boron is composed of two isotopes:
19.9% 10^B with a mass of 10.0129 amu
80.1% 11^B with a mass of 11.0093 amu.

Answer 23

1 amu.

electron

mass number.

two or more isotopes.

all the isotopes present in a naturally occurring sample of that element.

Question 24

Mass spectrometry:

The sample is vaporized and exposed to a high-energy electron beam that causes the sample’s atoms (or molecules) to :
These cations are then separated by :

Answer 24

Instrument used for the experimental measurement of the occurrence and natural abundances of isotopes

become electrically charged, typically by losing one or more electrons.

their mass and charge.

Question 25

Molecular Formula – A representation of a molecule or compound which consists of the following:

1)
2)

Answer 25

1) Chemical symbols to indicate the types of atoms.

2) Subscripts after the symbol to indicate the number of each type of atom in the molecule. Subscripts are used only when more than one atom of a given type is present.

Question 26

Structural Formula –

Ball-and-stick model -

Space-filling model -

Empirical formula –

Answer 26

A notation that shows the same information as a molecular formula but also shows how the atoms are connected.

A 3-dimensional representation of the molecules, showing the atoms and the chemical bonds between atoms.

A 3-dimensional representation that shows the relative sizes of the atoms that conform the molecules.

A representation that indicates the simplest whole-number ratio of the number of atoms (or ions) in the compound.

Question 27

Many elements consist of :

Some elements exist as :

Diatomic molecules: H2, N2, O2, F2, Cl2, Br2, I2

The most common form of elemental sulfur exists as S8.

Answer 27

discrete, individual atoms.

molecules.

Question 28

An empirical formula indicates the:

A molecular formula indicates:

Example: Benzene
Molecular formula = C6H6
empirical formula?

Answer 28

simplest whole-number ratio of the number of atoms (or ions) in the compound.

the actual numbers of atoms of each element in a molecule of the compound.

CH

Question 29

structural isomers:

Molecules of carvone are spatial isomers; they only differ in :

Answer 29

Compounds with the same chemical formula but different molecular structures.

the relative orientations of the atoms in space.

Question 30

periodic table

_______________ in _______ (_______) and ___________in ____________ (_________) independently recognized that there was :

For Example:
Lithium (Li), sodium (Na), and potassium (K) are all:

Calcium (Ca), strontium (Sr), and barium (Ba) are:

Answer 30

Dimitri Mendeleev in Russia (1869) and Lothar Meyer in Germany (1870) independently recognized that there was a periodic relationship among the properties of the elements known at that time.

For Example:
Lithium (Li), sodium (Na), and potassium (K) are all shiny, conduct heat and electricity well, and have similar chemical properties.

Calcium (Ca), strontium (Sr), and barium (Ba) are also shiny, conduct heat and electricity well, but are less reactive than Li, Na, and K.

Question 31

first periodic table

Both Mendeleev and Lothar Meyer published :

Mendeleev used his table to predict the :

The discoveries of ………… provided great support for Mendeleev’s work.

Answer 31

tables with the elements arranged according to increasing atomic mass.

existence of elements that would have the properties similar to aluminum and silicon but were not yet known.

gallium (1875) and germanium (1886)

Question 32

modern periodic table

By the twentieth century, it became apparent that:

Periodic Law is :

A modern periodic table arranges the elements in :

Periods or series –
Groups –

Answer 32

the periodic relationship involved atomic numbers rather than atomic masses.

The properties of the elements are periodic functions of their atomic numbers.

increasing order of their atomic numbers and groups atoms with similar properties in the same vertical column

• horizontal rows
  -vertical columns (numbered 1-18)

Question 33

Metals are :

Nonmetals appear :

Metalloids conduct :

Answer 33

shiny, malleable, good conductors of heat and electricity.

dull, poor conductors of heat and electricity.

heat and electricity moderately well and possess some properties of metals and some properties of nonmetals.

Question 34

Main group elements (or representative elements):

Transition metals:

Inner transition metals:

Answer 34

Groups: 1, 2, 13-18

Groups: 3-12

Two rows at the bottom of the periodic table.
Lanthanides – top row
Actinides – bottom row

Question 35

In ordinary chemical reactions, the nucleus of each atom (and thus the identity of the element) remains :

Electrons participate in chemical reactions by being:

The gain or lose of electrons, results in:

Answer 35

unchanged

-gained
lost
shared

the formation of ions.

Question 36

The periodic table can serve as a :

Many main-group metals :

Group 1 –

Group 2 –

Group 13 –

Answer 36

guide for predicting the ionic charge of main-group elements.

lose enough electrons to leave them with the same number of electrons as an atom of the preceding noble gas.

-lose one electron, form a cation with a 1+ charge.

lose two electrons, form a cation with a 2+ charge.

lose three electrons, form a cation with a 3+ charge

Question 37

Many non-metals gain enough electrons to give them the same number of electrons as

Group 17 –

Group 16 –

Group 15 –

Group 14 –

Answer 37

an atom of the next noble gas.

Group 17 – gain one electron, form an anion with a 1- charge.

Group 16 – gain two electrons, form an anion with a 2- charge.

Group 15 – gain three electrons, form an anion with a 3- charge

Group 14 – gain four electrons, form an anion with a 4- charge

Question 38

Predicting ion charge

Example: Ca (group 2)
Ca atom (20 protons, 20 electrons)
Loses 2 electrons
Now a :
Same number of electrons as the preceding noble gas, Ar.

Example: Br (group 17)
Br atom (35 protons, 35 electrons)
Gains 1 electron
Now a :
Same number of electrons as the next noble gas, Kr.

Answer 38

Ca2+ ion (20 protons, 18 electrons)

Br- ion (35 protons, 36 electrons)

Question 39

predicting ion charge

Moving from far left to far right in the periodic table:

Moving from the far right to the far left in the periodic table:

This method is less reliable for transition metals.
Cu forms ions of 1+ and 2+ charge.
Fe forms ions of 2+ and 3+ charge.

Answer 39

Positive charges of cations are equal to the group number.

Negative charges of anions are equal to the number of groups moved left from the noble gas.

Question 40

Monatomic ions are

Polyatomic ions are
examples:

Oxyanions are

Answer 40

ions formed from only one atom.

electrically charged molecules (a group of bonded atoms with an overall charge).
nitrate, nitrite, ammonium, peroxide, bicarbonate

polyatomic ions that contain one or more oxygen atoms.

Question 41

naming oxyanions

When a nonmetal forms two oxyanions
which is the suffix used for the ion with the larger number of oxygen atoms?
which is the suffix used for the ion with the smaller number of oxygen atoms?

When a nonmetal forms more than two oxyanions, prefixes are used along the suffixes
______ (largest number of oxygens)
______ (smallest number of oxygens)

Answer 41

-ate is the suffix used for the ion with the larger number of oxygen atoms.
-ite is the suffix used for the ion with the smaller number of oxygen atoms.

prefixes are used in addition to -ate and -ite
per- (largest number of oxygens)
hypo- (smallest number of oxygens)

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Question 42

When electrons are transferred…

Ionic bonds are :

When electrons are shared and molecules form, ….

Compounds are classified as …………… on the basis of:

Answer 42

ions form, and an ionic bond results.

electrostatic forces of attraction.

a covalent bond results.

ionic or molecular (covalent) on the basis of the bonds present in them.

Question 43

________ readily lose electrons –

_______ readily gain electrons –

When a metal and nonmetal react, ……

Metals and nonmetals generally form :

A compound that contains ions and is held together by ionic bonds is called :

Na and Cl
One Na atom gives up one electron forming a Na+ ion.
One Cl atom accepts that electron forming a Cl- ion.
The ionic compound, NaCl forms.

Ca and Cl
One Ca atom gives up two electrons forming a Ca2+ ion.
Two Cl atoms each accept one electron forming two Cl- ions.
The ionic compound, CaCl2 forms.

Answer 43

Metals; form cations.

Nonmetals; form anions.

a transfer of electrons usually takes place.

ionic compounds.

an ionic compound.

Question 44

properties of ionic compounds

-Typically solids with

-____________ in solid form.

-____________ in molten form.

Answer 44

Typically solids with high melting and boiling points.

Non-conductive in solid form.

Conductive in molten form.

Question 45

Ionic compounds are :

The formula of an ionic compound must have a :

These formulas are

Example: Al3+ and O2- , forms Al2O3
Two Al3+ ions gives six positive charges.
Three O2- ions gives six negative charges.

Answer 45

electrically neutral overall.

a ratio of ions such that the numbers of positive and negative charges are equal.

These formulas are not molecular formulas.

Example: Al3+ and O2-
Two Al3+ ions gives six positive charges.
Three O2- ions gives six negative charges.

Question 46

Ionic compounds can contain

Treat polyatomic ions as :

Parentheses in a formula are used to indicate :

Example: Ca2+ and PO43-, forms Ca3(PO4)2
Three Ca2+ ions gives six positive charges.
Two PO43- ions gives six negative charges.

Answer 46

polyatomic ions as the cation, the anion, or both.

discrete units.

a group of atoms that behave as a unit.

Question 47

Molecular compounds (______________) result when:

Exist as :

Usually formed by a

Often exist as :

Answer 47

(covalent compounds) result when atoms share electrons.

as discrete, neutral molecules.

a combination of nonmetals.

as gases, low-boiling liquids, and low-melting solids.

Question 48

Nomenclature –

Compounds are identified by

Answer 48

a collection of rules for naming things.

by both their formula and name.

Question 49

naming ionic compounds

first name: …… then:

A monoatomic cation is just given:

A monoatomic anion is given :

A polyatomic ion is just given :

how do i know which element is the cation and anion?

how to name polyatomic ions

Answer 49

Name the cation first, followed by the name of the anion.

the name of the element.

the name of the element with its ending replaced by the suffix –ide

the name of the ion.

Question 50

Naming ionic compounds containing a metal ion with a variable charge

Most of the transition metals can form :

The charge of the metal ion is specified by a :

Answer 50

two or more cations with different charges.

Roman numeral in parentheses after the name of the metal.

Question 51

Naming binary molecular (covalent) compounds

Molecular compounds are named using:

Covalent bonding allows for :

The names for molecular compounds must explicitly identify:

The more metallic element is:
Followed by :

The numbers of atoms of each element are designated by

When only one atom of the first element is present,:

When two vowels are adjacent, :

Answer 51

using a different set of rules.

for significant variation in the ratios of the atoms in a molecule.

identify these ratios.

named first.
the name of the more nonmetallic element with its ending changed to the suffix –ide.

Greek prefixes.

When only one atom of the first element is present, the prefix mono- is usually not used.

When two vowels are adjacent, the a in the Greek prefix is usually dropped.

Question 52

prefixes

Answer 52

mono-
di-
tri-
tetra-
penta-
hexa-
hepta-
octa-
nona-
deca-

Question 53

naming acids

Some compounds containing hydrogen are :

Many acids, when dissolved in water, release:

A mixture of an acid with water is given

1) The word “hydrogen” is changed to

2) The other nonmetallic element name is modified by

3) The word “_________” is added as a second word

Answer 53

are members of an important class of substances known as acids.

release hydrogen ions, H+

given a special name to denote this property.

1) The word “hydrogen” is changed to the prefix hydro-

2) The other nonmetallic element name is modified by adding the suffix –ic

3) The word “acid” is added as a second word

Question 54

naming oxyacids

Oxyacids - compounds that contain

They are bonded in such a way as to :

To name oxyacids:
1) Omit “_________”
2) Start with the
3) Replace :
4) Add “______”

Answer 54

hydrogen, oxygen, and at least one other element,

impart acidic properties to the compound.

To name oxyacids:
1) Omit “hydrogen”
2) Start with the root name of the anion
3) Replace –ate with –ic, or –ite with –ous
4) Add “acid”