2.1- The Nature of Matter Flashcards

1
Q

What is an Atom?

Subatomic particles that make up an atom:

A

the basic unit of matter

protons, neutrons, electrons

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2
Q

What is the nucleus?

A

the center of an atom that contains positivley charged protons, and neutrons with no charge

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3
Q

What are electrons?

A

negativley charged particles with almost no mass, and are in constant motion in the space surrounding the nucleus

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4
Q

Atoms have an ———– so they are neutral

A

equal number of electrons and protons

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5
Q

What is an element?

A

a pure substance that is entirely one type of atom

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6
Q

How are the elements orgainzed?

A

By atomic number (the number of protons each atom has)

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7
Q

What are isotopes

A

atoms of the same element that have a differnet number of neutrons

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8
Q

What is atomic mass number?

A

the total number of protons and neutrons in the nucleus

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9
Q

Radioactive isotopes are both:

A

extremly dangerous but helpful

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10
Q

What is a compound?

A

a substance formed by the chemical combination of 2 or more elements in definite proportions

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11
Q

A chemical formula:

A

shows the compostion of compounds

Ex: NaCl (table salt)

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12
Q

Physical and chemical properties of compounds are:

Example:

A

very differnet from the elements that form them

Chlorine is very reactive but forms sodium chloride which essentail for

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13
Q

Chemical Bonds:

A

hold atoms in compounds together

bond formation involves valence electrons (electrons in the outer shell)

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14
Q

What is an ionic bond?

A

When 1 or more electrons are transferred from one atom to another, resulting in ions that attract to each other becuase of their opposite charges

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15
Q

What is an ion?

A

when an atom loses or gains electrons and becomes positively or negatively charged

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16
Q

What is a covalent bond?

A

when atoms ‘share’ electrons; the electrons travel around both nuclei

17
Q

What are single, double, and triple covalent bonds?

A

Single: 2 shared electrons
Double: 4 shared electrons
Triple: 6 shared electrons

18
Q

What is a molecule?

A

the smallest unit of most compounds; formed when atoms are jioned by covalent bonds

19
Q

What are van der Waals forces?

A

when molecules are close together and a slight attration develops between the oppositely charged regions of nearby molecules

Ex: geckos

20
Q

Atoms are:

A

the building blocks of matter

21
Q

What is chemistry?

A

the study of matter’s composition and properties

22
Q

Matter:

A

anything that has mass and takes up space

23
Q

Who propsed the idea that all matter is made up of tiny particles?

A

Greek Philosophers Leucippus and Democratis

24
Q

When did scientists begin to collect evidence to support the existence of atoms?

A

1800s

25
Q

Dimitri Mendeleev:

late 1800s, Russian

A

orgainized the elements based on increasing atomic mass

26
Q

Henrey Mosely:

A

led movemnet to organize the elements by atomic number, not mass

27
Q

What is the purpose of neutrons?

A

to prevent protons from repeling each other

(same charges repell, think of magnet)

28
Q

Electrons determine:

A

the chemical properties of atoms

Electron cloud, properties determined by electrons in the outer orbit

29
Q

Example of electron property:

A

hydrogen is very reactive becuase it has only 1 electron and wants 2 to become for stable

30
Q

What element does not have a neutron

A

hydrogen

31
Q

How do you determine the number of neutrons of an element?

A

subtract the number of protons from the atomic mass

Atomic mass is the average of the isotopes too

32
Q

When you increase the number of neutrons in an atoms…

A

the atoms begins to degrade making it radioactive (affects stability)

33
Q

What is Carbon-14 used for?

A

to determine the age of fossils and to locate and treat some cancers

found in all living things

34
Q

What is radioactive iodine used for?

A

to treat thyroid cancer

35
Q

What is radioactive barium used for?

A

to detect abnormalities in the gastrointinal tract

(MRI replaced this)

36
Q

How many compounds are there?

A

millions

37
Q

Wetlands produce how much of global methane?

A

76%

38
Q

Liquids and gasses are formed by:

A

covalent bonds

Examples: water, methane, hydrochloric acid

39
Q

Solids are formed by:

A

ionic bonds