ATOMS, MOLECULES, AND IONS Flashcards

1
Q

proposed the concept of fire, air, water, and earth to explain the composition of matter.

A

Empedocles (490-435 B.C.)

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2
Q

proposed the existence of a fifth element which he called quintessence.

A

Aristotle (384-323 B.C)

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3
Q

came up with a theory stating that everything is composed of small indivisible particles which he called atomos.

A

Democritus (460-370 B.C.)

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4
Q

____ proposed that atoms have fixed weights and definite properties.

A

John Dalton

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5
Q

’ experiment about the cathode rays helped English physicist

A

Sir William Crookes

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6
Q

_____ discover the electron in 1897

A

J.J. Thomson

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7
Q

_____ determined the charge of an electron in 1909.

A

Robert Millikan

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8
Q

_____ gold-foil experiment helped him elucidate the existence of the nucleus.

A

Ernest Rutherford’s

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9
Q

_____ suggested that the total energy of an electron is quantized.

A

Niels Bohr

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10
Q

The _______ of mass states that the mass of the products in a chemical reaction will always be equal to the mass of the reactants.

A

law of conservation

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11
Q

The ______ states that all the samples of a chemical compound contain all the elements in the same proportion.

A

law of constant composition

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12
Q

The ________ states that the elements in a compound have a proportion of those chemical compounds that can be expressed in a small, whole-number ratio.

A

law of multiple proportions

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13
Q

An ____ is a small, indivisible particle considered as the basic unit of matter.

A

atom

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14
Q

____ are positively-charged particles located inside the nucleus.

A

Protons

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15
Q

_____ are small, negatively-charged particles that spin around the nucleus.

A

Electrons

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16
Q

____ have no charge and are also located inside the nucleus.

A

Neutrons

17
Q

The _______ is equal to the number of protons inside the nucleus.

A

atomic number (Z)

18
Q

The _________ is the sum of the number of protons and the number of neutrons in the nucleus.

A

mass number (A)

19
Q

_____ are kinds of the same element that have the same number of protons, but different numbers of neutrons.

A

Isotopes

20
Q

_____ of an element have the same atomic number but different mass numbers.

A

isotopes

21
Q

_________ uses special X-rays to obtain images from different angles of the body.

A

Computed Axial Tomography (CT Scan)

22
Q

uses a strong magnetic field and radiofrequency waves, also providing cross-sectional images that allow doctor to diagnose diseases inside the body.

A

Magnetic Resonance Imaging (MRI) MRI

23
Q

______$ is a new experimental cancer therapy which selectively destroys cancerous tissues without harming the healthy surrounding cells.

A

Boron Neutron Capture Therapy (BCNT)

24
Q

_____ are atoms that are chemically bonded together.

A

Molecules

25
Q

Molecules can occur in nature as ____ or ___.

A

diatomic ; polyatomic

26
Q

A ____ molecule contains only two atoms

A

diatomic

27
Q

A ____ molecule contains three or more atoms.

A

polyatomic

28
Q

____ are atoms or molecules that have a charge, meaning, the number of protons is not equal to the number of electrons, giving the atom either a positive or a negative net charge.

A

lons

29
Q

A _____ formula is a way of expressing the elements present in a compound in symbols, as well as the number of atoms of each element present in the compound.

A

chemical

30
Q

A _____ formula is a graphical representation of the compound using the symbol of the elements to indicate how the atoms are arranged and bonded chemically.

A

structural

31
Q

A _____ formula is a formula that shows the atoms present in a compound, as well as the number of atoms per element present in it.

A

molecular

32
Q

An _____ formula is a formula that shows the simplest form of the atomic ratio in a chemical compound.

A

empirical

33
Q

A ___ is a representation of a compound’s molecular structure.

A

model

34
Q

A _____ model depicts the 3-dimensional view of the atoms of a compound and the bonds between them.

A

ball-and-stick

35
Q

• A ____ model depicts the atoms of the compound using spheres that are joined together, approximating the actual sizes of the atoms.

A

space-filling

36
Q

An ionic compound is a ____ compound that contains a cation and ananion.

A

neutrally-charged

37
Q

A _______ is made up of only one atom.

A

monoatomic ion

38
Q

A _____ ion is made up of more than one atom of different elements

A

polyatomic

39
Q

A _____ compound is composed of nonmetallic elements

A

molecular