chem 103-- chap 2 Flashcards
Atoms, Molecules, and Ions
definition of element
fundamental substance that can’t be chemically changed or broken down
how many elements are there?
118
what is the most abundant element in the human body and on the earth’s crust
oxygen
periodic table definition
organized chart of elements with their names, symbols, and other info
who arranged the elements in a table to show that there were more elements to be found
Dmitri Mendeleev
what are periods
organized 7 horizontal rows
what are groups in the periodic table
18 vertical colomns
how are the elements arranged in the periodic table
they are grouped by similar chemical properties
property definition
any characteristic to describe or identify matter
what are examples of properties
volume, amount, odor, color, temp
what is an intensive property
temp and melting point don’t depend on amount of the sample
what is an extensive property
(length and volume) depend on amount and sample size
what is a physical property
Any property you can see, smell, touch, hear or otherwise detect and measure without performing a chemical reaction
chemical property
characteristics involve a change in chemical makeup
what are the elements in group 1A named?
alkali metals
what are the elements in group 2A named?
alkaline earth metals
what are the elements in group 7A named?
halogens
what are the elements in group 8A named?
Noble gases
where are the nonmetals location
mostly on the right side of the table, besides helium
what elements are best conductors of electricity
metals
noble gas porperties
colorless gas
low reactivity
helium and neon don’t combine w/ any other element
halogen properties
only found in nature w/ another element
colorful, cohesive metals
alkaline earth metal properties
silvery metals
less reactive than 1A
alkali properties
high reactivity
react with water rapidly
(hydrogen is in group one, but isn’t a alkali)
What is the largest category of elements
metals
How many semi metals are there? and where are they located?
7 elements and they are diagonal on the right side between the metals and nonmetals
what are chemical compounds
atoms of different elements joining together in different ways to yield a vast number of different substances
what is a chemical formula
lists the symbols of it’s constitutes and uses subscripts to indicate number of atoms EX: NaCl
what is a chemical equation
reactant substances undergoing changes written out to see the change EX: 2HgO –> 2Hg + O2
law of mass conservation definiton
mass is neither created nor destroyed in chemical reactants
law of definite proportions definiton
different samples of a pure chemical compound always contains the same proportions of the elements by mass
law of multiple proportions definiton
elements can combine in different ways to form different chemical compounds, whose mass ratios are simple WHOLE NUMBER multiplier of each other
what is Dalton’s theory
elements are made up of atoms
same mass of elements = same element
atoms never change, just their ratios
what are atoms
tiny particles that make up elements
what is Thompson’s experiment
Cathode-ray tube–
high voltage electric currents going from a negative electrode, to a positive electrode. Proposed electrons were in the metals
3 things that affect magnetic deflection
strength of deflecting magnet
size of negative charge on electron
mass of electron
what is an ionic bond
share electrons by transferring 1+ of them
what are ions
charged particles
what are cations
positive ions, (by losing electrons)
what are anions
(by gaining electrons)
Are cations typically metals or nonmetals?
Metals
are anions typically metals or nonmetals?
nonmetals
what is an ionic solid
equal numbers of ions packed together with opposite attractions EX: Na+ & Cl-
what are polyatomic ions?
charged covalent groups of atoms
what are binary ionic compounds
2+ elements in a ionic compound
When writing a binary ionic compound, how do you write it?
positive ion 1st
negative ion 2nd
add “ide” at the end
what two categories fall under pure substances
elements and chemical compounds
what experiment did Millikan conduct
mist voltage experiment and found electron mass
What was Rutherford’s experiment?
found nucleus in atoms by shooting alpha particles through foil & and having some of them reflect
nucleus defintion
tiny central core in atom
what is the nucleus composed of?
Protons and electrons. elements differ in size of nucleus based on how many they have
proton defintion
positively charged; opposite charge of electron
neutron defintion
no charge, equal mass to protons
atomic number defintion
number of protons IN the nucleus and number of neutrons AROUND the nucleus
EX: helium= atomic number 2= 2 protons
mass number defintion
number of protons and neutrons in an atom
isotope defintion
identical atomic number but diff. mass and diff. amounts of neutrons
atomic mass defintion
specific atom’s mass; numerically close to mass number
atomic weight defintion
average of natural isotope masses of an element
how do you mathematically find atomic weight of an element?
(element 1 mass)(abundance) + (element 2 mass)(abundance)
what is a mole
SI unit for amount
what is molar mass
amount of mass of an element in grams to moles
mixture
blend of 2+ substances w/o chemical change
chemical compound
atoms of different elements combining into a new substance
chemical bonds
electrons forming connections to join atoms together into compounds
covalent bonds
2 atoms sharing 2+ electrons
what is the most common bond type?
covalent bonds
what is a molecule
result of 2+ atoms joined together by covalent bonds
what do ball-stick models show?
atoms connected together by covalent bonds
what do space filling models show?
show molecular shape but not bonds
structural formula
shows specific connections
diatomic molecules
molecules whose same atoms are held together by covalent bonds
what are diatomic elements
H2 N2 O2 F2 Cl2 Br2 I2
