Chapter 4 - Atoms and Elements Flashcards
Atoms
- smallest identifiable unit of an element
- makes up matter
Element
subctance that cannot be broken down
Chemical Bonds
joins elements
Dalton’s Atomic Theory
1 each element is composed of tiny indestructible particles called atoms
2 all atoms of a given element have the same mass and other properties that distinguish them from the atoms of other elements (UNTRUE)
3 atoms combine in simple whole-number ratios to form compounds
MOLECULES
only 2 or more atoms joined together
Compounds
2 or more different atoms
-all compounds are moles but not all moles are compounds
subatomic particles
electron, proton, neutron
Plum Pudding Model Theory
- suggested by JJ Thomson
- electrons are embedded into a cake-like cake/pudding
- later proved wrong
Rutherford’s Nuclear Theory of an Atom
- tiny particles called alpha-particles were directed at a thin sheet of gold foil
- most of the particles passed directly through the foil via deflection (sometimes at sharp angles)
MEANING: inside an atom is something dense (nucleus) in which particles hit it and ricochet. surrounding the nucleus are free space in which electrons move around.and particles pass through.
Atomic Number
- number of Protons which identifies the element
- represented by the letter Z
Metals
- LEFT side of the periodic table
- tend to LOSE electrons
- good conductors of heat and electricity
- malleable
- ductile
- often shiny
Nonmetals
- UPPER- RIGHT side of the periodic table
- tend to GAIN electrons
- some are solid, some are gases
- O, N, Cl, I
Metalloids or Semimetals
- along the zigzag portion of the periodic table
- semimetals - displays mixed properties
- SEMICONDUCTORS bc intermediate conductivity which can be changed and controlled
- used in electronics often
Main Group elements
- contains both metals + nonmentals
- has predictable properties based on their position in periodic table
- 1A, 2A, 3A-8A
Transition Metals/Elements
middle area of periodic tables
-columns labeled by number and letter B
Alkali Metals
1A
- very reactive
ex) Na and K
Alkaline Earth Metals
2A
- reactive
ex) Ca, Mg
Halogen
7A
-very reactive nonmetals bc wants to fill in the 1 open space
Noble Gases
8A
-content/stable; full orbitals; wont bond w other elements to form compounds
Cations
positive ions (usually metals)
Anions
neg ions (usually nonmetals)
Ions
in chem rxn, atoms often lose or gain electrons to form charged particles
Ion Charge
ion charge = (#protons+) - (#electrons-)
ion charge = #p+ - #e-
ex) Li has 3 p and loses 2 e: ion charge =3-2=1+
ex)F has 9 p and gained 1 e (9+1=10) ion charge =9-10=1-
Isotopes
- atoms w same number of protons but diff. number of neutrons
- ALL elements have their unique percent of NATURAL ABUNDANCE of isotopes
ex) Neon has 10 protons but can have 10, 11, or 12 neutrons.
Isotope Symbol
A (p + n) CHEM.SYMBOL.
Z (p)
or CHEM.SYMBOL- A (p+n)
ex) 20/10 Ne or Ne-20
Polyatomic Ions
one type of compound that is charged
Polyatomic Ions
one type of compound that is charged
Nuclear Theory of an Atom
1 most of the atom’s mass and all of its positive charge are contained in a small core called NUCLEUS
2 most of the volume of an atom is empty space w electrons dispersed
3 there are neg charged electrons outside of the nucleus and protons inside the nucleus so ATOMS ARE NEUTRAL
Atom’s Nucleus
makes up 99.9% of atom’s mass
-contains protons and neutrons
Atomic Mass Unit
amu
- defined as 1/12 the mass of carbon containing 6 protons and 6 neutrons
- mass of proton and neutron are nearly identical
- it is an average mass of an element’s atom since diff isotopes vary in weight
mass of proton
1.672 x 10^-27kg
mass of neutron
1.674 x 10^-27kg
Chemical Symbol
A 1 or 2 letter abbreviation for the element
malleability
ability to be pounded to flat sheets
ductility
ability to be drawn into wires
Family or Group of Elements
-each column within the periodic table
Percent Natural Abundance
- for a given element, the relative amounts of each isotope in a naturally occurring sample of that element are always the same
ex) in any natural sample of Neon, 90.48% has 10 neutrons, 0.27% has 11 n, and 9.25% has 12 n
Atomic Mass formula
atomic mass = (%xisotope mass) +(%xisotope mass) and so on
ex) Cl has 75.7% Cl-35 (mass is 34.97amu), 24% Cl-37 (mass 36.97amu)
atomic mass=(0.7577x34.97amu) + (0.2423x36.97amu)
=35.45amu
Isotopes vs Ions
ions differ in electrons
isotopes differ in neutrons
