Unit 2: The Atom & Electromagnetic Energy

The smallest particle of an element that retains the properties of an element

an Atom

The three main subatomic particles that make up the structure of an atom

• protons +

• neutrons 0

• electrons -

A nucleus contains what subatomic particles

Protons and neutrons

Any pure substance made up of only one type of atom and cannot be broken down

Element e.g gold

When two or more atoms are chemically bonded together, also smallest particle of a compound

Molecule 0²

→ can be the same element or different element

A molecule made of two or more different elements chemically bonded together

Compound h²0

All _____ are molecules

Compounds

*ACAMMACA

Not all ____ are molecules

Compounds

*ACAMMACA

Consists of two more substances that are physically mixed but not chemically bonded

Mixture e.g air

Elements are made out of _____

Compounds are made out of _____

1. Atoms

2. Molecules

2n²

The maximum # electrons in each shell with n representing the shell number

List the electron shells least to greatest

K → L → M → Q (Valence shell)

Closest to the nucleus has ____ binding energy and are held ____ tightly

Higher, more

Farther to the nucleus has ____ binding energy because they are held ___ tightly

Lower, less

Required to remove an electron from its orbit (shell)

Electron binding energyA

Atomic Number (Z) measures the # of _____

# of protons

→ determines identity of element

Atomic Mass (A) equals the # of ____

total # protons AND neutrons aka nucleons

Formula to calculate mass number

A = Z + N

A = mass #

Z = atomic #

N = number of neutrons

Formula to calculate elemental notation

A

X

Z

X = element symbol

A = mass number (protons + neutrons)

Z = atomic number (# of protons)

N = number of neutrons ( N = A - Z )

What type of atom has an equal number of protons and electrons

Neutral (stable) atom

An atom that gains or loses electrons causing it to have an unequal number of protons

Ionized atom

Type of ion when an atom loses one or more electrons (more protons than electron

Positive ion

Type of ion when an atom gains on or more electrons (more electrons than protons)

Negative ions

Type of chemical bond when one atom transfers it’s electron to another atom

Ionic bond

Type of chemical bond that shares electrons between atoms

Covalent bond

Same number of protons but have different numbers of neutrons

Isotope

Same number of neutron but have different number of protons

Isotone

Same number of mass but have different atomic number (Z)

Isobar

Occurs when at atom’s nucleus is unstable and needs to release energy or particles to become stable

Radioactivity

→ AKA radioactive decay or disintegration

Period of time required for a quantity of radioactive atoms to be reduced too ½ its original value

Half life

3 main types of radioactive decay

• Alpha particles

• Beta particles

• Gamma decay

The nucleus emits an alpha particle leaving two protons and two neutrons, decreasing the mass by 4 and therefore changing the element. Low penetrating ability but harmful if enter body

Alpha decay (alpha emission)

A neutron inside nucleus changing into proton emitting a high-spreed electron, therefore increasing its atomic number by 1. A new element is formed but mass remains the same. Moderate penetrating ability

Beta Decay

To become stable nucleus removes extra energy in form of gamma ray (high energy electromagnetic radiation AKA photons) therefore having no mass and no charge and doesn’t change element identity. Greatest penetrating ability, through human body but also help in medicine.

Gamma Emission

What’s emitted during an Alpha Decay. How does atomic number and mass change, and what stops its penetration?

2 protons and 2 neutrons

• Atomic number decrease by 2, atomic mass decrease by 4

→ Paper

What’s emitted during a Beta Decay. How does atomic number and mass change, and what stops its penetration?

High speed electron produced by nucleus

• Atomic number increases by 1, atomic mass stays same

→ aluminum

What is emitted during a Gamma Decay? How does atomic number and mass change, and what stop’s its penetration?

High energy electromagnetic radiation (photons)

• Atomic number and atomic mass remain the same

→ lead

Waves created as a result of vibrations between electrical and magnetic fields

Electomagnetic Waves

Transfer energy as they travel through matter ex. sound and water

Mechanical Waves

Don’t need matter to transfer energy ex: x-ray, light

Electromagnetic Waves (EM)

Oscillation of up and down patterns to represent electromagnetic energy

Sine waves

The distance between one crest to another

Wavelength (λ)

The distance a wave rises of falls from its position

Amplitude

# of waves (cycles) that pass in a second and measured in Hz

Frequency

The higher the frequency the (higher, lower) the energy

higher

3 characteristics of EM waves

• Travel at speed of light 186,000 miles/sec or 3×10^8 m/s

• Travel through anything/ a vacuum

• Have all properties waves: wavelengths, frequency, and amplitude

When frequency _____, wavelength decrease

Increases

Frequency and wavelength are inversely proportional

When frequency ____, energy decreaess

Decreases

Frequency and energy are directly proportional

Formula to calculate the speed of a wave

C = frequency x wavelength

(C= 3 × 10^8 m/s p0

eV = (4.15 × 10^-15) x frequency

Calculates the relationship between frequency and energy

The smaller the wavelength the ____ the energy

Higher

Wavelength is measured in

Angstrom (A)

As energy increases, wavelength ______

Decreases

Energy and wavelength are inversely proportional

Formula to measure wavelength

keV = 12.4 / λ (wavelength)