elements and periodic table

Question 1

what is a pure substance in called in chemistry

Answer 1

substance

Question 2

what can be a pure substance

Answer 2

an element or compound

Question 3

what is a pure substance

Answer 3

one that has the same composition and properties throughout

Question 4

what are elements

Answer 4

substances made up of one type of atom

Question 5

who used a chemical symbol to represent elements

Answer 5

swedish scientist jon berzelius

Question 6

what are chemical symbols derived from

Answer 6

the first and maybe second letter of its latin name

Question 7

how many elements occur naturally

Answer 7

90

Question 8

how many elements have been created or synthesized by humans

Answer 8

19

Question 9

who created the periodic table

Answer 9

dmitri mendelev

Question 10

what does the atomic number represent

Answer 10

the amount of protons in an atom

Question 11

where are the lanthanide and actinide series located

Answer 11

bottom of the periodic table

Question 12

what is each entry in the periodic table called

Answer 12

a tile

Question 13

what are the horizontal rows in the periodic table called

Answer 13

periods

Question 14

what are the vertical columns in the periodic called

Answer 14

families or groups

Question 15

do elements in a group have different properties

Answer 15

no

Question 16

do elements in a period have different properties

Answer 16

yes

Question 17

which group is the halogen

Answer 17

VII A

Question 18

where are metals found

Answer 18

on the far left of the periodic table

Question 19

where are metalloids

Answer 19

in the middlish

Question 20

where are non-metals found

Answer 20

on the far right

Question 21

what does the reactivity of an element depend on

Answer 21

the number of valence electrons

Question 22

what are valence electrons

Answer 22

the number of electrons found in the outermost energy level of an atom

Question 23

the group numbers in a periodic table are equal to what

Answer 23

the number of valence electrons

Question 24

what is the atomic mass of an element equal to

Answer 24

the number of protons plus neutrons

Question 25

what are isotypes

Answer 25

atoms of the same element that have different numbers of nuetrons

Question 26

what happens in a neutral atoms

Answer 26

the number of protons is equal to the number of electrons

Question 27

atoms are usually what

Answer 27

nuetral