Chemistry: Atoms & The Periodic Table

How large are atoms?

Really small and you can only see them with a special microscope

How big is the nucleus?

1 millionth the volume of an atom

Where is 99.9% of the mass of an atom?

In the nucleus

What particles are in the nucleus?

Protons & nuetrons

What si the charge of a proton?

+1

Where are protons located?

In the nucleus

What defines an element?

The number of protons

What is the mass of a proton?

1amu or 1.6673^24

What charge does a neutron have?

0 (no charge)

Where are neutrons located?

In the nucleus

True or false: the number of neutrons can vary in an atom

true

What is the mass of a neutron?

1amu

What is the charge of an electron?

-1 charge

How many electrons are in a neutral atom?

The same number as the number of protons

Where are electrons located?

In the electron cloud

What is the electron cloud?

where electrons swirl around the nucleus billions of times per second

If an atom has more energy, will there be a larger or smaller electron cloud?

larger

What is the mass of an electron?

around 0amu

What is the abbreviation for a proton?

p+

What is the abbreviatoin for a
neutron?

n0

what is the abbreviation for an electron?

e-

Who discovered the proton?

Rutherford

When was the proton discovered?

1919

Who discovered the neutron?

Chadwick

When was the neutron discovered?

1932

Who discovered the electron?

Thomson

When was the electron discovered?

1897

What are elements?

building blocks of all matter and made up by atoms

What is atomic number?

The number of protons in an element

Does the atomic number ever change for an element?

No

What is the mass number?

Sum of protons + neutrons?

What is Atomic Mass (Atomic Weight)

weighted average mass of all isotopes in an element

What are isotopes?

The same atoms but with different numbers of neutrons

What are ions?

Atom with a charge

What does being an ion mean?

That the number of electrons isn't equal to the number of protons

What is a cation?

An atom with more protons than electrons

What is an anion?

An atom with more electrons than protons?

What is electromagnetic force?

force that keeps electrons in orbit around the nucleus

What particles in the atom does EMF hold together

protons and electrons

What particles in the atom does EMF push apart

protons + protons and electrons + electrons

What is Strong Nuclear Force?

strongest force that holds the nucleus together

What particles does SNF hold together

protons + neutrons

What force does SNF counteract?

EMF

What occurs when SNF breaks down?

Alpha and fission radioactivity

What is radioactivity?

act of emitting radiation spontaneously when unstable atoms undergo changes within their nuclei

What atoms can have radioactivity?

All atoms beyond #83 (Polonium)

What is Alpha decay

When EMF overpowers SNF and the SNF can no longer hold the nucleus together so it ejects a stable group of particles to reduce the EMF

What is nuclear fission?

when heavy nucleus is hit with a high energy particle and the nucleus breaks into two smaller nuclei along with a leftover "shrapnel"

What is weak nuclear force?

a force that holds together particles called quarks that make up p+ and n0

What happens when WNF breaks down?

Beta Decay occurs

Why does beta decay happen?

when there's too many neutrons in the nucleus and WNF causes one quark to flip and turn a nuetron into a p+ and an e-

What types of decay causes the element to change?

Alpha and Beta decay

What is gravitational force?

force of atraction between all objects

What is Gamma decay?

when energy is released in a high energy photon because the nucleus contains too much energy

What is the most peneratrable type of decay?

Gamma

What is the least penetrable type of decay?

Alpha

Who created the periodic table increase by atomic mass?

Mendeleev in 1869

How did Mosely contribute to how the Periodic Table looks today?

He rearragned the table by Atomic Number in 1914

Who was Seaborg?

In 1944 he rearranged the Periodic Table with Lanthanide and Actinide series?

What is the most abundant element in the universe?

Hydrogen

What are groups/families?

Collums (up and down)

What are periods?

Rows (left to right)

What type of elements are in group 1?

Alkali metals

What type of elements are in group two?

Alkaline earth metals

Where are transition metals?

Groups 3-12

Where are chalcogens?

Group 16

What type of element is in group 17?

Halogens

What type of element is in group 18?

Noble Gases

Where are metalloids?

On either side of the staircase (besides Al)

Where are most nonmetals?

On the right side of the staircase

What qualities to metals have?

They're good conductors of heat & electricity, malleable, ductile, high melting points, shiny and tend to lose electrons

What qualities to nonmetals have?

They're poor conductors of heat & electricity, brittle when solid, low melting points, dull and tend to gain electrons

What qualities do metalloids have?

They're so-so conductors of heat & electricity, medium melting points, shiny or dull and properties between metals & nonmetals

What increases when you go down a family/group?

Number of energy levels

What increases when you go across a period?

Number of valence electrons

How many periods are on the Periodic Table?

7

What elements ar ein Period 1?

Hydrogen and Helium

What periosd to the langthanides and actinides belong to?

6&7

What two important things does the period tell us?

Period number is the number of energy levels in the atom and across a period, chemical and physical properties change because number of valence electrons changes

What is the Periodic Law?

The physical and chemical properties of the elements are period functions of their atomic number (patterns/properties repeat)

How many groups are on the Periodic Table

18

What are valence electrons?

the elecrrons found in the outer energy level and are important for chemical bonding

What are two important things that the group tells us?

The number of valence electrons and that within a family/group the properties are very similar because they have the same valence electrons

What is atomic radius?

an atoms size from the center of the nucleus to the outer energy levels of an electron cloud

When does the atomic radius increase?

When you go down a group in the periodic table

When the atomic radius decrease?

when you go across the periodic table from left to right

Why does the atomic radius increase as you go down a group?

Becuase the number of energy levels increase going down a group and more energy levels = a bigger atom. Also valence electrons are further from the nucleus so EMF isn't pulling in electrons as tightly

Why does atomic radius decrease going across the periodic table?

Because the number of valence elctrons increases across a period and more protons and more electrons mean more EMF pulling electrons towards the nucleus so valence electrons are held in more tightly and the radius is smaller.

metals tend to ____ valence electrons

lose

Going down a family of metals, the number of energy levels ____

increases

metals father down a group mroe easily give up their valence electrons making them ____

more reactive

nonmetals tend to ____ electrons

gain

nonmetals towards the top of the family are ____ reactive

more

noble gases are ___

not reactive

what are toxins?

substances that are toxicc and can cause harm, injury &/or death

what is a poison?

a toxic substance that is injaled, injested. or absorbed

what is a venom?

toxic substance that is secreted by an animal and injected by a bite or sting

What is the octet rule?

charge an atom has in order to achieve noble gas status or a full valence shell

what is reactivity?

tendency of an atom to gain or lose electrons in order to achive a full outer energy level (octet)

What is oxidation number?

preffered ionic charge in order for atom to achieve octet