1: Atoms and Elements

Question 1

What is an atom?

Answer 1

• Smallest particle of matter
• Cannot be chemically divided
• Atomos: indivisIble
• Smallest component of an element

Question 2

Explain Aristotle and Democritus’ views

Answer 2

A: atoms can be split forever (continuous theory), matter is divisible, 4 elements; water, fire, earth, wind
D: atoms cannot be split forever (discont.), matter is made of atoms, space between them, atoms can be different creating different objects/bodies

Question 3

Define a theory, model, and law

Answer 3

Theory: “why?” beginning of an idea, set of principles explaining an aspect of reality
Model: manual made to see the inner workings of things too big or too small
Law: accepted statement explaining what’s happening based on data/observations

Question 4

Explain Dalton’s theory

Answer 4

Atoms are empty, super tiny, can’t be divided, all atoms of the same element are identical, different atoms = diff. properties (mass, size), chemical reactions form new ones without creating, dividing, or destroying, only rearranging

Question 5

What did Lavoisier theorize?

Answer 5

The law of conservation of matter: nothing is created, destroyed, only transformed. Total mass of reactants = total mass of product (first scientific theory on the nature of matter)

Question 6

Explain Thomson’s theory

Answer 6

Cathode ray tube experiments leads to the discover of electrons (atoms emit light when electrified), proved that they’re neg. charged inside a pos. ball, follow a straight path, is divisible, plum pudding model

Question 7

Explain Rutherford’s theory

Answer 7

Gold foil experiment, emitted alpha particles to the gold foil. most passed through but some bounced back or deflected, learned that they were mostly empty. but the matter was mostly concentrated in the middle: nucleus with pos. charge protons. Greater atom mass = bigger nucleus.

Question 8

Explain the quantum theory

Answer 8

When an electron receives a quantum of energy, it jumps to a further orbital to release it and returns to its original shell. This distance creates a light wave of colour.

Question 9

What is the periodic table?

Answer 9

It is a way to classify elements according to certain patterns in their properties, both chemical and physical

Question 10

Describe Metals and its location on the table

Answer 10

To the left of the staircase

• Good conductors (elec., heat)
• Ductile and malleable
• Shiny
• Solid at room temp (except mercury)
• Many react with acids, release hydrogen

Question 11

Describe NonMetals and its location

Answer 11

To the right of the staircase

• Poor conductors
• Brittle, dull
• Mostly gasses at room temp.
• No reactions to acid

Question 12

What is an alloy?

Answer 12

A mixture of metals/non metals, combining qualities from all the elements they’re composed of

Question 13

Describe metalloids and their location

Answer 13

On either side of the staircase, have properties of both other categories, ex: pyrex in cookware

Question 14

Why is hydrogen #1 on the periodic table?

Answer 14

Though it is a nonmetal, it is located in column one due to its properties and atomic structure (1 v. e.)

Question 15

Why are elements in groups (columns)?

Answer 15

Elements have the same chemical properties because they have the same # of v. e.

Question 16

What signifies a stable atom?

Answer 16

When the valence shell is full by gaining, losing, or sharing electrons during a chemical reaction (whichever is easiest) ie: 2 v.e. will lose 2, 6 v.e. will gain 2. This is how bonds form to create molecules.

Question 17

What signifies an atom’s chemical reactivity?

Answer 17

How fast it can gain/lose v.e. (the faster, the higher the reactivity) 1v.e./7v.e. are more reactive cause they are closer to reaching a full shell

Question 18

What are the octet and duet rules?

Answer 18

Octet: needs a full valence shell of 8 v.e.
Duet rule (H, Li, He, B, Be): full valence shell of 2 v.e.

Question 19

Describe alkali metals

Answer 19

• G1A, except H
• Soft, light
• Low melting point
• Excellent conductors
• Highly reactive (stored in oil to avoid contact w air moisture)
• Found in halogen compounds, forming salts,

Question 20

Describe alkaline earth metals

Answer 20

• G2A
• Harder, malleable, grey
• High melting point
• Excellent conductors
• Less violent reactions (burn easily but can be exposed to air)
• Found in rock compounds
• Halogen compounds forming salts

Question 21

Halogens

Answer 21

• G7
• Coloured
• React easily to alkali metals, forming compounds (salts)
• React w hydrogen to form acids
• Toxic, corrosive, bactericidal

Question 22

Noble gases

Answer 22

• G8
• Colourless
• Emit colour when electrified (quantum theory)
• Stable, full shell (low reactivity)
• Found in elemental state in nature

Question 23

What is an isotope?

Answer 23

Forms of an element with different numbers of neutrons, same chemical properties but different physical properties

Question 24

What is the atomic radius trend?

Answer 24

More protons = more attraction between e. and nucleus. Higher attraction = smaller nucleus since it’s pulled more tightly tgt. Within a period, the atomic radius decreases. Going down a group it increases because the number of shells gets bigger.

Question 25

What is the ionization energy trend?

Answer 25

Energy required to remove the outermost electron from its atoms, thus creating an ion: atom with a charge else than zero. Higher ion energy = more energy required to remove an electron since it is more attracted to the nucleus. IE increase as AR decreases

Question 26

What is the electronegativity trend?

Answer 26

Attraction to another atom’s electrons. How likely it is to gain electrons. Higher value = more likely to gain. The less shells, the closer the electrons, higher attraction. EN is higher at the right of the periodic table, since they almost have a full shell.

Question 27

What is the chemical reactivity trend?

Answer 27

How likely/vigorously an atom will react with other substances based on the number of v.e.. The closer they are to obtaining a full shell, the more reactive.

Question 28

What is lewis notation?

Answer 28

Symbol + number of v.e. surrounding it’s “four walls” with dots