Chapter 3: Atoms

Question 1

atom

Answer 1

fundamental unit of matter

Question 2

Democritus

Answer 2

Greek philosopher who suggested that matter is make up of “indivisible” particles called atoms

Question 3

Antoine Lavoisier

Answer 3

French chemist who observed that the total mass before and after a chemical reaction is the same, or the law of conservation of mass

Question 4

John Dalton

Answer 4

English chemist who introduced the atomic theory

Question 5

atomic theory

Answer 5

a scientific explanation for the nature of matter and chemical reactions

Question 6

according to the atomic theory, elements are made up of

Answer 6

tiny, indivisible particles called atoms

Question 7

according to the atomic theory, the atoms of each element are

Answer 7

unique; atoms of different elements are different

Question 8

according to the atomic theory, atoms can join together in whole-number ratios to form

Answer 8

compounds

Question 9

according to the atomic theory, atoms are ________ in chemical reactions

Answer 9

unchanged

Question 10

Dimitri Mendeleev

Answer 10

Russian scientist who organized the known elements into a table based on their atomic masses and arranged elements with similar properties into columns

Question 11

periods

Answer 11

horizontal rows on the periodic table

Question 12

in a period, all elements have the same

Answer 12

number of electron shells

Question 13

the next element in a period has one more

Answer 13

proton; it is less metallic than its predecessor

Question 14

groups

Answer 14

columns on the periodic table

Question 15

in a group, elements have similar

Answer 15

chemical properties and the same number of valence electrons

Question 16

main-group elements

Answer 16

the left and right-hand blocks of the periodic table

Question 17

transition metals

Answer 17

elements in the middle of the periodic table; tend to be harder and less reactive than the metals in the first two columns

Question 18

inner transition elements

Answer 18

the two additional rows at the bottom of the periodic table

Question 19

the first row of the inner transition elements is called the

Answer 19

lanthanide series; it contains heavier, naturally occuring metals called rare earth metals

Question 20

the second row of the inner transition elements is called the

Answer 20

actinide series; the first few elements (up to uranium) are naturally occuring and the elements after are mostly human-made

Question 21

metals

Answer 21

elements that are solid at room temperature, malleable, and conduct heat and electricity

Question 22

nonmetals

Answer 22

elements found on the upper right side of the periodic table; physical properties vary widely

opposite of metals

Question 23

metalloids

Answer 23

elements in a stairstep pattern between metals and nonmetals; are semi-conductors

Question 24

alkali metals

Answer 24

elements that lie on the far left of the periodic table in column 1A; they are soft metals that react violently with air or moisture

Question 25

alkaline earth metals

Answer 25

elements in column 2A that are also reactive but not as much as alkali metals; they react slowly with water and burn brightly when combined with oxygen

Question 26

halogens

Answer 26

elements in column 7A that exist as diatomic molecules in their elemental form; they react quickly with metals and other nonmetals to form different compounds

Question 27

noble gases

Answer 27

elements in column 8A that are stable and do not react with other elements to form compounds; they are gases at room temperature

Question 28

nucleus

Answer 28

tiny, dense center of an atom

Question 29

subatomic particles

Answer 29

smaller components of an atom - protons, neutrons, and electrons

Question 30

proton

Answer 30

positively charged particle located in the nucleus with a mass of 1.0073 u

Question 31

electron

Answer 31

negatively charged subatomic particle with a mass of 0.0005 u

Question 32

neutron

Answer 32

neutral subatomic particle in the nucleus with a mass of 1.0087 u

Question 33

J.J. Thomson

Answer 33

English physicist credited with the discovery of the electron; assumed that atoms must also contain positive charges to balance the negative charge

Question 34

Plum Pudding model

Answer 34

model of J.J. Thomson's theory; hypothesized that electrons were spread throughout a positive atomic substance the way blueberries are scatteried in a muffin

Question 35

atomic number (Z)

Answer 35

the number of protons in an atom

Question 36

mass number

Answer 36

the sum of the number of protons and neutrons in an atom

Question 37

isotopes

Answer 37

atoms that have the same atomic number but have different mass numbers

Question 38

in an isotope, the mass number is written at the

Answer 38

upper left-hand side of the chemical symbol; the atomic number is written at the lower left-hand side

Question 39

Bohr model

Answer 39

atomic structure model consisting of the nucleus in the center and electrons surrounding it in orbits

Question 40

quantum model

Answer 40

modern description of electronic behavior; electrons behave both as particles and waves

Question 41

because electrons occupy the outer volume of the atom, they can

Answer 41

sometimes lose or pick up electrons from neighboring atoms to form ions