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Law of conservation of mass

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Mass is neither created nor destroyed during ordinary chemical reactions or physical changes

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Law of definite proportions

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A chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound

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Law of multiple proportions

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If two or more different compounds are composed of the same two elements then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers

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Dalton turned Democritus' idea into a

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Scientific theory that could be tested by experiment

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Cathode ray

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Stream of particles

question

Cathode rays are

answer

Negatively charged

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Cathode Rays have identical properties regardless of

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The element used to produce them

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Cathode ray experiments provides evidence that atoms are

answer

Divisible

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Who measured the charge of the electron

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Robert A. Millikan

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Because atoms are electrically neutral they must contain a

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Positive charge to balance the negative electrons

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Because electrons have so much less mass than atoms, atoms must contain

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Other particles that account for most of their mass

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Thomson proposed a model for the atom called the

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Plum pudding model

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Thomson believed negative electrons were

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Spread evenly throughout the positive charge of the rest of the atom

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Ernest Rutherford bombarded gold foil with

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Alpha particles

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The gold foil experiment led to the discovery of the

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Nucleus

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The nucleus was very

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Small compared to the total volume of an atom

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Niels Bohr proposed a model in which

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Electrons surrounded the positively charged nucleus

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All nuclei are made of two kind of particles

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Protons and neutrons

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Atoms are electrically neutral because they contain

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Equal numbers of protons and electrons

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The number of protons determines the

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Atoms identity

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When two protons are extremely close to each other there is a

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Strong attractions between them known as nuclear forces

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Electron cloud

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Cloud of negative charge

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Atomic number

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Number of protons of each atom of that element

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An elements atomic number is located

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Above its symbol

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The most common type of hydrogen is called

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Protium

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Protium, deuterium and tritium are

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Isotopes of hydrogen

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Isotopes

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Atoms of the same element that have different masses

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The isotopes if a particular element all have the same number of

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Protons and electrons but different numbers of neutrons

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Mass number

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Total number of protons and neutrons that make up the nucleus of an isotope

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Two methods for specifying isotopes

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Hyphen notation and nuclear symbol

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Nuclide

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General term for a specific isotope of an element

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The standard used by scientists to compare units of atomic mass is the

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Carbon-12 atom

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One unified atomic mass unit

answer

Is exactly 1/12 the mass of a carbon-12 atom

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Isotopes or an element may occur

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Naturally or in a laboratory

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Although isotopes have different masses, they do not

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Differ significantly in their chemical behavior

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Average atomic mass

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Weighted average of the atomic masses of the naturally accounting isotopes of an element

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Mole

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Amount of a substance that contains as many particles as there are atoms

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Number of particles in a mole

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Avagadro's number

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One wave/second is a

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Hertz

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Max Planck proposed that

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A hot object would be expected if the energy emitted were in the form of waves

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Quantum of energy

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E= hv

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Electron orbits can be compared to

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Rungs on a ladder

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Atomis means

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Not to cut or indivisible

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Aristotle said that

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Matter could be cut continuously

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Most of an atom is

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Empty space, dense positive,t charged core

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Neutral atoms contain equal numbers of

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Protons and electrons

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Rutherford's gold foil experiment led him to conclude that

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A dense region of positive charge existed somewhere in the atom

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What is not one of the five principles of Dalton's theory

answer

All atoms gave similar physical and chemical properties

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According to the law of definite proportions any two samples of KCI will have

answer

The same elements in the same proportions by mass

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According to the law of conservation of mass when sodium hydrogen and oxygen react to form a compound the mass of the compound will be

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Equal to the sum of the masses of the reactants

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Thomsons experiment showed that the charge to mass rail of electrons was

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The same in all gases

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An atom has 19 protons and 20 neutrons. It's mass number is

answer

39

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Compared with a mole of lead atoms a mole of its on atoms has

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The same number of atoms

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The molar mass of an element is numerically equal to

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The elements average atomic mass

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The units of molar mass are

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g/mol

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To determine the mass in grams of an atom of any element you would

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Divide the mass of a mole of the element by Avagadro's number

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The average atomic mass of an element is

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The weighted average of all naturally occurring isotopes of the element

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The Ancient Greek philosopher that first proposed the notion of the atom was

answer

Democritus

question

Which feature or Dalton's atomic theory is different from modern atomic theory

answer

Atoms can not be subdivided

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The least massive particle in an atom is

answer

Electron

question

The most massive particle in an atom is

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Neutron

question

Protons are bound together by

answer

Strong nuclear forces

question

Under what condition is a photon emitted from an atom

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When an electron moved from a high energy level to a low energy level

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What do quantum numbers describe

answer

Energy level, orbital shape, orbital orientation and spin state

question

What is the relationship between the principal quantum number and the electron confuguration

answer

N describes the energy level

question

List five examples of electromagnetic radiation

answer

Gamma rays, x Rays, ultraviolet light, infrared light, microwaves, radio waves

question

What two experiments involving light and matter could not be explained by the wave theory of light

answer

Photoelectric effect and line emission spectrum

question

How is hydrogen's emission spectrum produced

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When electrons drop from higher energy orbits to lower energy

question

What was a shortcoming of Bohr's model of the atom

answer

Did not explain chemical nature of atoms

question

What is the principal quantum number and how is it symbolized

answer

n- main energy level

question

What are shells

answer

All orbitals with the same energy level

question

The Aufbau principle

answer

Electron occupies lower energy orbital that can receive it

question

Hund's rule

answer

Orbitals of equal energy are occupied by 1 electron before being occupied by a second

question

Pauli exclusion principle

answer

No 2 electrons in the same atom can have the same 4 quantum numbers

question

What are inner shell electrons

answer

Electrons that are not in the highest occupied energy level

question

How does noble gas notation simplify writing electron configurations

answer

Abbreviate large portions of the configuration

question

A photon is emitted from a gaseous atom when an electron moves to its ground state from an

answer

Excited state

question

When electromagnetic radiation strikes the surface of a metal, electrons are ejected from the metal surface. This is a description of the

answer

Photoelectric effect

question

What describes the angular momentum number indicate

answer

The shape of an orbital

question

What type of electromagnetic radiation had the lowest frequency

answer

Microwaves

question

What can behave like a wave and also a stream of particles

answer

Electromagnetic radiation.

question

When an atom in an excited state emits a photon of radiation the energy of the photon is equal to the

answer

Difference in energy between the atom's excited state and its final stage

question

The total number of orbitals that can exist at a given energy level is

answer

2n squared

question

How many possible orientations does an s orbital have

answer

1

question

How many possible values are there for the spin quantum number

answer

2

question

In cathode ray tubes, the cathode ray is emitted from the negative electrode which is called the

answer

Cathode

question

The smallest unit of an element that can exist either alone or in molecules containing the same or different elements is the

answer

Atom

question

The behavior of cathode Rays in a glass tube containing gas at low pressure led scientists to conclude that the rays are composed of

answer

Negative particles

question

The basic principles of atomic theory were first conceived by

answer

Dalton

question

Neutral atoms of the same element can differ in

answer

Mass number

question

The law of multiple proportions is demonstrated by the compounds

answer

CO and CO squared

question

Millikans experiments led to the determination of the

answer

Approximate value of the electrons mass

question

S orbitals are

answer

Spherical

question

P orbitals are

answer

Dumbbell shaped

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D and F orbitals are

answer

More complex

question

Level 1

answer

S

question

Level 2

answer

S P

question

Level 3

answer

S P D

question

Level 4

answer

S P D F

question

1st quantum number

answer

N- principal quantum number

question

2nd quantum number

answer

L- orbital shape within an energy level

question

3rd quantum number

answer

M- orientation of orbital in space

question

4th quantum number

answer

S- spin of electron in orbital

question

No two electrons in the same atom can have the same set of four quantum number

answer

Pauli Exclusion Principle

question

N L M S are used to describe an

answer

Electron in an atom

Chemistry Unit 2 Test Questions – Flashcards

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