2.1- The Nature of Matter

Question 1

What is an Atom?

Subatomic particles that make up an atom:

Answer 1

the basic unit of matter

protons, neutrons, electrons

Question 2

What is the nucleus?

Answer 2

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

Question 3

What are electrons?

Answer 3

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

Question 4

Atoms have an ———– so they are neutral

Answer 4

equal number of electrons and protons

Question 5

What is an element?

Answer 5

a pure substance that is entirely one type of atom

Question 6

How are the elements orgainzed?

Answer 6

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

Question 7

What are isotopes

Answer 7

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

Question 8

What is atomic mass number?

Answer 8

the total number of protons and neutrons in the nucleus

Question 9

Radioactive isotopes are both:

Answer 9

extremly dangerous but helpful

Question 10

What is a compound?

Answer 10

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

Question 11

A chemical formula:

Answer 11

shows the compostion of compounds

Ex: NaCl (table salt)

Question 12

Physical and chemical properties of compounds are:

Example:

Answer 12

very differnet from the elements that form them

Chlorine is very reactive but forms sodium chloride which essentail for

Question 13

Chemical Bonds:

Answer 13

hold atoms in compounds together

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

Question 14

What is an ionic bond?

Answer 14

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

Question 15

What is an ion?

Answer 15

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

Question 16

What is a covalent bond?

Answer 16

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

Question 17

What are single, double, and triple covalent bonds?

Answer 17

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

Question 18

What is a molecule?

Answer 18

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

Question 19

What are van der Waals forces?

Answer 19

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

Ex: geckos

Question 20

Atoms are:

Answer 20

the building blocks of matter

Question 21

What is chemistry?

Answer 21

the study of matter’s composition and properties

Question 22

Matter:

Answer 22

anything that has mass and takes up space

Question 23

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

Answer 23

Greek Philosophers Leucippus and Democratis

Question 24

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

Answer 24

1800s

Question 25

Dimitri Mendeleev: | late 1800s, Russian

Answer 25

orgainized the elements based on increasing atomic mass

Question 26

Henrey Mosely:

Answer 26

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

Question 27

What is the purpose of neutrons?

Answer 27

to prevent protons from repeling each other | (same charges repell, think of magnet)

Question 28

Electrons determine:

Answer 28

the chemical properties of atoms | Electron cloud, properties determined by electrons in the outer orbit

Question 29

Example of electron property:

Answer 29

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

Question 30

What element does not have a neutron

Answer 30

hydrogen

Question 31

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

Answer 31

subtract the number of protons from the atomic mass | Atomic mass is the average of the isotopes too

Question 32

When you increase the number of neutrons in an atoms...

Answer 32

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

Question 33

What is Carbon-14 used for?

Answer 33

to determine the age of fossils and to locate and treat some cancers | found in all living things

Question 34

What is radioactive iodine used for?

Answer 34

to treat thyroid cancer

Question 35

What is radioactive barium used for?

Answer 35

to detect abnormalities in the gastrointinal tract | (MRI replaced this)

Question 36

How many compounds are there?

Answer 36

millions

Question 37

Wetlands produce how much of global methane?

Answer 37

76%

Question 38

Liquids and gasses are formed by:

Answer 38

covalent bonds | Examples: water, methane, hydrochloric acid

Question 39

Solids are formed by:

Answer 39

ionic bonds