Chapter 4 Flashcards
According to Dalton’s Atomic theory Elements are composed of _________.
atoms; tiny, hard, unbreakable spheres
According to Dalton’s Atomic theory all atoms of a given element are ___________.
identical; atoms of different elements are different, every carbon atom is identical to every other carbon atom, but carbon atoms are different than sulfur atoms
According to Dalton’s Atomic theory atoms combine in _____, __________ ratios to form ________ of ___________
- simple
- whole number
- molecules
- compounds
Atoms combine as whole atoms because…
atoms are unbreakable
Each molecule of a compound contains the exact same ______ and ________ of atoms
- types
- numbers
- law of constant composition* - i.e. H2O will always contain 2 Hydrogens and 1 Oxygen; Hydrogen peroxide will always have 2 hydrogens and 2 oxygens
According to Dalton’s Atomic theory atoms are not _______ or ________ into another type during a chemical rxn.
- broken
- changed
*all atoms present before the reaction are present after
According to Dalton’s Atomic theory atoms are not ______ or _______they are just ________
- created
- destroyed
- rearranged
- therefore the total mass will remain the same this is called the law of conservation of mass.
Can atoms change into a different type of atom during a chemical reaction?
No, atoms of one element do not change into Adams of another element in a chemical reaction.
Lead cannot be turned into gold via chem. rxn
Scientists such as JJ Thomson and others showed that atom had pieces called __________
electrons
Thomson discover about electrons?
He discovered that electrons are smaller than atoms and carry a negative charge of 1-
1 e-
One electron with a charge of one minus
5 e-
Five electrons with a total charge of five minus
Chemical reactions _______atoms.
rearrange
CH4 + O2 —–> CO2 + H2O
A (3g) + B (5g) = C + D (?)
8g
law of conservation of mass
Two kinds of charge_______and ______.
positive
negative
If you have to positively charged magnets will they attract or repel?
repel, because like charges repel and opposite charges attract.
an atom has the same number of protons and electrons what is the atom’s charge?
the atom is neutral.
If something has no charge, or the same number of charges what is it called?
neutral
What are the significant points of Rutherford’s interpretation of the nuclear model?
- the atom contains a tiny dense center called the nucleus.
- The nucleus has essentially the entire mass of the atom.
- The nucleus is positively charged.
- the electrons move around in the empty space of the atoms surrounding the nucleus.
how much space does the nucleus of an atom take up?
1/10 trillionth of the volume of the atom
Trying to contribute to the mass of an atom?
Yes but the amount of mass they contribute is so insignificant that they practically give no mass to the atom.
Positively charged particles are called __________.
Protons
*Protons have a positive charge of 1+
Who proposed that there was a positively charged particle in the nucleus of an atom that has the same amount of charges an electron?
Rutherford
he discovered this based on measurements of the nuclear charge of elements
1p+
one proton
5p+
five protons
in order for an atom to be neutral it must have the same amount of _______ and _____.
protons
electrons
because p+ and e- have the same amount of charge
In addition to the proton Rutherford proposed the existance of another type of subatomic particle in the nucleus called the ___________.
neutron
What is the charge of a neutron?
neutrons have no charge.
The masses of protons and neutrons are approximately ___________.
the same
1n0
1 neutron
5n0
five neutrons
the nucleus of an atom contains _______ and _______.
protons
neutrons
what is the diameter of the nucleus of an atom?
10^-13
What are the 3 subatomic particles that make up an atom?
proton
neutron
electron
e- move outside the nucleus with an average distance of about 10^-8 cm ….
therefore the radius of the atom is about 100,000 times larger than the radius of the nucleus.
AMU
atomic mass unit; a common unit to express mass for atoms.
a proton has the mass of
~ 1 amu
a neutron has the mass of
~ 1 amu
an electron has the mass of
~ 0 amu
if the charge of an atom changes the amount of which subatomic particle has changed?
the amount of e- because if the amount of p+ changes then the element changes because an atom of a certain element always has the same number of p+
each element has a ___________ number of protons in its nucleus.
unique
atomic number
the number of protons in the nucleus of an atom
How are the elements on the periodic table of elements arranged?
in order of their atomic numbers
Each element has a unique ____ and _______.
name
symbol
the symbol is made up of one or two letters One capital letter by itself or with a lowercase letter.
Z= 11
an atom has 11 protons because Z represents atomic number which is the number of protons in an atom.
Z
atomic #= # of protons
What is Z of Boron?
5
atomic mass
the mass of an atom of a chemical element expressed in atomic mass units. It is approximately equivalent to the number of protons and neutrons in the atom (the mass number) or to the average number allowing for the relative abundances of different isotopes.
Mendeleev
- organized the elements according to atomic mass
- while doing this he recognized a repeating pattern of properties
- Periodic law
- he used the pattern he discovered to predict the properties of undiscovered elements
Periodic law
when the elements are arranged in order of increasing relative mass, certain sets of properties recur periodically.
What are the 7 metalloids?
- Boron
- Silicon
- Germanium
- Arsenic
- Antimony
- Tellurium
- Astatine
Boron
Z = 5
Atomic mass: 10.81 amu
Symbol: B
Silicon
Z = 14
Atomic mass: 28.09 amu
Symbol: Si
Germanium
Z = 32
Atomic mass: 72.63 amu
Symbol: Ge
Arsenic
Z = 33
Atomic mass: 74.92 amu
Symbol: As
Antimony
Z = 51
Atomic mass: 121.75 amu
Symbol: Sb
Tellurium
Z = 52
Atomic mass: 127.60 amu
Symbol: Te
Astatine
Z = 85
Atomic mass: 210 amu
Symbol: At
Metals
- solid at 25 degrees Celsius except for mercury
- reflective shiny surface
- conducts heat well
- conducts electricity well
- malleable
- ductile
- loses e- and becomes a cation in chem rxns
- 75% of elements are metals
- lower left on the table
Nonmetals
- poor conductors of heat and electricity
- solids are brittle
- gains electrons in chem. rxns (becomes anions)
- if already has extra e- it won’t want more
- upper right on the table except hydrogen
Metalloids
- show some properties of metals and nonmetals
- also known as semi conductors
*ex. silicon (metalloid) is shiny, brittle conducts electricity but does not conduct heat well (semiconductor)
In the modern periodic table of elements, how are elements with similar chemical and physical properties grouped?
elements with similar chemical and physical properties are grouped in in columns called groups or families
*families are labled by a number and a letter at the top of a column
In the modern periodic table of elements rows are called ____________.
periods
‘A’ groups
main group
‘B’ group
transition elements (all metals)
Inner Transition Elements
bottom rows
Group 1A
Alkali metals
- hydrogen is placed here though it doesn’t belong
- soft low melting points
- low density
- flame test; Li = red, Na = yellow, K = violet
- very reactive
- never find uncombined in nature
what type of sodium is included in our diet?
Na+
Why are chemicals reactive?
chemicals are reactive when they are unstable, they will react because they are looking for stability; if an element is unreactive it is stable
What are the Alkali metals?
Lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr)
Group 2A
Alkaline Earth metals
- harder than alkali metals
- higher melting point
- denser
- flame tests; Ca = red, Sr = red, Ba = yellow-green
- reactive but less than corresponding alkali metal
What are the Alkaline earth metals?
Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba)
Group 7A
Halogens
- nonmetals
- F2 and Cl2 gases; Br2 liquid,; I2 solid
- all diatomic (more stable as a pair)
- very reactiveHelium
What are the Halogens?
Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I)
Group 8A
Noble gases
- all gases at room temperature (very low melting and boiling points)
- very unreactive practically inert
- very hard to remove e- from or give an e- to.
What are the noble gases?
Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe)
The number of protons determines the _____________.
element; all Na atoms have 11 protons
In a chemical change the number of protons in an atom does not __________.
change
electrically charged atoms in a compound are called?
ions
+ cation
- anion
How do atoms acquire a charge?
by gaining or losing e- (NOT PROTONS!)
Ion charge =
protons - # electrons
Cations
positive charge
made by losing e-
more protons than e-
usually metals
Anions
negative charge
made by gaining e-
more e- than protons
usually form from nonmetals
Na+
sodium ion (cation)
What kind of ions do metals form?
cations
How are cations named?
cations are named the same as the metal but with ion added on
The charge of a cation can be determined from the _______number on the periodic table.
group;
Group 1A —-> 1+, Group 2A —-> 2+ (Al, Ga, In) —–> 3+
Na vs. Na +
sodium and sodium ion
Ca and Ca 2+
Calcium and calcium ion
nonmetals tend to gain ________.
e-
How are nonmetals (anions) with a charge named?
base name of nonmetal + ide +ion
O vs O2-
oxygen and Oxide ion
Base names for Nonmetals
H: hydr 1- N: nitr 3- P: phosph 3- O: ox 2- S: sulf 2- F: fluor 1- Cl: chlor 1- Br: brom 1- Se: selen 2- I: iod 1- Te: tellur 2-
The charge on an anion can be determined from the group ________ on the _________ -______
number
periodic table
*Group 7A —>1-
Group 6A—>2-
Isoelectronic
different elements with the same number of e-
isotope
atoms of an element that are the same but have different weights *discovered by Soddy
Identical elements with different masses due to different numbers of neutrons
There are 2 isotopes of chlorine found in nature, one that has a mass of about 35 amu and another that weighs 37 amu why is the atomic mass on the periodic table of elements for chlorine 35.45 amu?
because there is more Chlorine-35 in nature; The observed mass is a weighted average of the weights of all the naturally occuring atoms
How do isotopes differ?
Allz isotopes have the same protons but different numbers of neutrons
isotopes of an element have different masses
How are isotopes identified?
isotopes are identified by their mass numbers (A) Protons+neutrons
A
mass number (protons+neutrons)
Atomic number
Z
number of protons
Mass number
A
whole number
Protons+neutrons
isotopic notation
Ne-21
Atomic Symbol
A/Z X = X-A
A= mass number Z= atomic number X= element
Atomic mass
represents the average mass for each element
found directly beneath element symbol
All isotope percentages should equal ________.
100%
