Unit 2 Learning Check

Question 1

John Dalton (1766-1844)

Answer 1

• English chemist whose ideas formed the atomic theory of matter

Question 2

Atomic Theory of Matter

Answer 2

• all elements are composed of atoms; it is impossible to destroy an atom
• all atoms of the same elements are alike
• atoms of different elements are different
• atoms of different elements combine to form a compound; these atoms have to be in definite whole number ratios

Question 3

J. J. Thompson (Late 1800s)

Answer 3

• English scientists who discovered the electron when he was experimenting with gas discharge tubes
• he noticed a movement in the tube, which he called cathode rays
• the rays moved from the negative end of the tube to the positive end; the rays were made of electrons (negative particles)

Question 4

Lord Ernest Rutherford (1871-1937)

Answer 4

• conducted the gold foil experiment
• used gold foil and special equipment to shoot positive alpha particles at the foil
• particles passed straight through the foil, but some were deflected
• discovered that atoms were made of a small positive nucleus since it repelled the alpha particles and that atoms are mostly empty space

Question 5

Niels Bohr (Early 1900s)

Answer 5

• Danish physicist who proposed a model of the atom that looks like the solar system
• he claimed electrons orbit the nucleus and that they are on their own energy levels (level 1 can hold 2 electrons max, level 2 can hold 8, level 3 can hold 18, and level 4 can hold 32)
• when electrons release energy they go down a level, and when they gain energy they go up

Question 6

Atomic Number

Answer 6

• number of protons
• identity of an atom

Question 7

Mass Number

Answer 7

• total number of protons and neutrons

Question 8

Isotope Representation

Answer 8

• element symbol then minus sign then mass number (ie Sr - 90)

Question 9

Nuclear Symbol

Answer 9

top left corner is mass number, middle is element symbol, bottom left is atomic number

Question 10

Isotope

Answer 10

• atoms of the same element having the same atomic number but different mass number
• or they could have the same number of protons but different number of neutrons

Question 11

In what order are the elements arranged on the periodic table?

Answer 11

in increasing order based on their atomic number

Question 12

Period

Answer 12

• horizontal rows on the periodic table
• 7 total

Question 13

Groups/Families

Answer 13

• vertical columns on the periodic table
• 18 total

Question 14

Metals Location

Answer 14

on the left, center, and bottom of the periodic table

Question 15

Non-Metals Location

Answer 15

towards the right on the periodic table

Question 16

Atomic Mass

Answer 16

• the weighted average of masses for each individual isotope of an element

Question 17

Atomic Mass Equation

Answer 17

atomic mass (amu) = (mass #1 x % #1) + (mass #2 x % #2) + ……