CH 4 Atoms & Elements

Atom

smallest part of an element

consists of nucleus (protons/neutrons) and electrons

Neutrons

subatomic particle found within nucleus

carries no charge

Protons

subatomic particle found within nucleus

carries positive charge

Electrons

smallest subatomic particle

carries negative charge and spins around the nucleus

electron cloud is 1,000,000 times larger than nucleus

Two major forces that characterizes behavior between protons and neutrons

Nuclear Force and Electrostatic Force

Nuclear Force

force within nucleus that pulls together protons and neutrons

Electrostatic Force

force within the nucleus that pulls apart protons and neutrons

What must be true for a stable nucleus that is held together?

Nuclear Force must be greater than Electrostatic Force

T or F: The nucleus has an overall neutral charge

F

AMU

atomic mass unit

used to calculate relative mass of an atom or subatomic particle

1 AMU =

one-twelfth the mass of a carbon-12 atom

1 Dalton (DA) named after John Dalton “Father of Chemistry”

1.66×10^-27 kg

Isotopes

elements with the same number of protons but different number of neutrons

Atomic Number (Z)

provides number of protons

determines identity and chemical properties of an element

Mass Number (A)

provides number of protons + neutrons

To calculate neutrons

mass number - atomic number

Ions are created from…

elements losing or gaining electrons to obtain a stable electronic arrangement

Cation

lose electrons to become positively charged

Anion

gain electrons to become negatively charged

A metal tend to … while non-metals tends to…

lose electrons, gain electrons

Isoelectronic

elements that have the same number of electrons

The atomic mass of an element is an average of…

all its isotopes that uses the units of g/mol, amu, Da

Calculate subatomic particles for 88/38 Sr

38 protons, 50 neutrons, 38 electrons

Calculate subatomic particles for 34/16 S

16 protons, 18 neutrons, 16 electrons

Calculate subatomic particles for 27/13 Al 3+

13 protons, 14 neutrons, 10 electrons

Calculate subatomic particles for 81/35 Br 1-

35 protons, 46 neutrons, 36 electrons

In which pair are the two species both isoelectronic and isotopic?

23/11 Na 1+ and 24/11 Na 1+

Calculate subatomic particles for Co 3+

27 protons, 32 neutrons, 24 electrons

Calculate subatomic particles for Se 2-

34 protons, 46 neutrons, 36 electrons