regents chemistry topic 2 the periodic table and formulas / equations
TRANSCRIPT
Regents Chemistry
Topic 2
The Periodic Table and Formulas / Equations
Regents Chemistry
Introduction to the TableGroups and FamiliesElements of Metals, Nonmetals and
Metalloids
Recap
Nucleus
electrons
•The nucleus contains protons and neutrons
•Electrons surround the nucleus in a “cloud”
•Atomic number is the number of protons
•Atomic mass is the sum of protons and neutrons
The Periodic Table
The periodic table is arranged according to Atomic Number
The first table, by Russian chemist Dmitri Mendeleev, was arranged by atomic mass, but this was not accurate
Current arrangement shows many important trends..
Rows and Columns
Divisions of the Periodic Table
MetalsAlkali metalsAlkaline earth metalsTransition Metals
Metalloids
NonmetalsHalogensNobel gases
Periodic Table
Physical Properties of Metals
1. Efficient conduction of heat and electricity
2. Malleability (they can be hammered into
thin sheets
3. Ductility (they can be pulled into wires)
4. A lustrous (shiny) appearance
Natural States of ElementsMost of the matter around us consists of mixtures
Mixtures contain compounds
Atoms of individual elements are not often found in nature in pure form Some exceptions: gold, platinum and silverAlso noble gases – do not combine readily
Ex; Helium gas in underground deposits
Elements after Separation..
After we use a chemical process to separate the elements in a compound, we find the elements to be:Monoatomic atoms– only (1) atom of the
elementDiatomic molecules– (2) atoms bonded
together
Examples
Argon (noble gas)
Nitrogen and
oxygen
Natural Physical States
Metals are solids at 25 C
Noble gases are gas at room 25 C and are individual atoms
Several others are gases and diatomic at 25 C – (H2, N2, O2, F2, Cl2)
Only two elements are liquids at 25 CBromine and Mercury
Elements can have different forms…
Solid metals differ from solid non-metalsIn fact, different forms of the same element can occurThese are called allotropes
Ex: CarbonDiamond (very hard)Graphite (soft)Buckministerfullerene (newly discovered)
End
Regents Chemistry
Information on the TableAverage Atomic MassAtomic Number Isotopes
Regents Chemistry
Periodic Table Bingo
Regents Chemistry
Ions and Oxidation States
**Change ending of parent name to -ide and add word - ion**
Cloride Anion
***Keep parent name and add word - ion***
Sodium Cation
Ionic charges from Periodic Table
See pg. 112
Writing out ionic charges
Sodium ion
Magnesium ion
Gain e-
Losee-
Ionic Compounds
Combination of cation and anionWrite cation first and anion second
When combining, we must consider electrical charge Ions combine in such a way to make a zero
net chargeTotal chargeof cations
+ Total chargeof anion
= Zero net charge
Examples
More Examples...
=
worksheet
Dissolving Ionic CompoundsVideo
Does this work?
Regents Chemistry
Chemical Nomenclature
Naming Compounds
Common names were originally developed to name compoundsEx: Epsom salts, milk of magnesia,
gypsum and laughing gas
Too many common names..a system had to be developed!
Naming Compounds
Binary compounds – compounds that are composed of two elements
We will examine two classes of binary compounds1. Compounds that contain a metal and a
nonmetal 2. Compounds that contain two nonmetals
Naming Binary Ionic Compounds
Binary ionic compounds result when a metal combines with a nonmetalThe metal loses electrons as the nonmetal gains electronsThe result is a positive cation (the metal) and a negative anion (the nonmetal)In naming ionic compounds, we simply name the ions
We will learn how to name two types of ionic compounds (polyatomic ion naming will come later)Type I compounds – The metal is present in
only one type of cation - look at periodic table!Ex: Na+, K+, Ca2+, Al3+
Type II compounds – The metal present can form two (or more) cations that have different charges - look at periodic table!
Ex: Cr2+, Cr3+, Cu+, Cu2+
Naming Binary Ionic Compounds
Some Common Examples
Cation Name Anion Name
H+ Hydrogen F- Fluoride
Li+ Lithium Cl- Chloride
K+ Potassium Br- Bromide
Ca2+ Calcium I- Iodide
Ag+ Silver S2- Sulfide
Naming Rules for Type I Ionic
1. The cation is always named first and the anion second
2. A simple cation (obtained from a single atom) takes its name from the name of the element. Ex: Na+ Sodium ion
3. A simple anion (obtained from a single atom) is named by taking the first part of the elemental name and adding – ide Ex: F- Fluoride ion
ExamplesName the following compounds
• NaCl
• KI
• CaS
sodium chloride
potassium iodide
calcium sulfide STOPworksheet
CLICK TO REVEAL ANSWERS
Regents Chemistry
Naming Type II Compounds
Naming Type II compounds
Type II compounds – The metal present can form two (or more) cations that have different charges - look at periodic table!
Ex: Cr2+, Cr3+, Cu+, Cu2+
We cannot only look at the periodic table to determine the charge…we must determine the charge according to the chemical formula
Determing the correct charge
All compounds must be electrically neutral..so
we use the charge of the anion to determine the charge of the cation…and multiply the charges by the number of atoms to determine the overall net charge
Example
CuCl
Cl comes in as Cl- : -1 x 1 Cl ion = -1
Cu must come in as a +1 :+1 x 1 Cu ion = +1
-1 + +1 = 0 , the charges balance
Copper (I) Chloride
Naming Type II Rules
Use the same system of naming as Type I binary compounds..except
add the following after the cation depending on the cation’s charge
(I) +1 (V) +5(II) +2 (VI) +6(III) +3 (VII) +7(IV) +4
Practice
HgO
Fe2O3
Mercury (II) Oxide
Iron (III) Oxide
Worksheet
Regents Chemistry
Naming Type III Binary Compounds
Non-metal to non-metal
Type III Binary Compounds
Type III Binary Compounds - are compounds that contain only nonmetals participating in covalent bonds (sharing of electrons)
Rules for Naming Type III1. The first element in the formula is named first, and the full element name is used
2. The second element is named as though it were an anion (-ide ending)
3. Prefixes are used to denote the numbers of atoms present.
4. The prefix mono is never used for naming the first element
Prefixes for Naming Type III
PREFIX NUMBER INDICATED
mono- 1di- 2tri- 3tetra- 4penta- 5hexa- 6hepta- 7octa- 8
Practice
BF3
NO
N2O5
carbon tetrachloride
boron trifluoride
nitrogen monoxide
dinitrogen pentoxide
CCl4
worksheet
Regents Chemistry
Polyatomic Ion Compound Nomenclature
What’s a polyatomic ion?
A polyatomic ion consists of two or more elements bonded together that posess an overall net charge that can be used to form an ionic bond with a metal cation
We looked at some of these!
SO42-
Polyatomic Ion Intro…
Polyatomic ions have specific names…You must be able to recognize polyatomic ions in chemical formulas and chemical namesYou reference tables can help! See the table on the front page
Naming Polyatomic Ions…
Some polyatomic ions have general names that are made from modification of the names of the elements involvedEx: NH4
+ Ammonium Ion
CN- Cyanide Ion
Naming Oxyanions
Oxyanions are polyatomic ions (anions) that contain atoms of an element and different numbers of oxygen atoms
When there are two members in such a series, the anion with the lesser number of oxygen is given the ending –ite and the larger number ends in –ate
SO32- SO4
2-Sulfite Ion
Sulfate Ion
If there are more that two in the series, we use the prefix hypo for the member with the fewest oxygen and per for the one with the most oxygen
Naming Oxyanions cont…
ClO- hypochlorite ion
ClO2- chlorite ion
ClO3- chlorate ion
ClO4- perchlorate ion
Naming Compounds that Contain Polyatomic Ions…
We use the cation name and roman numerals (if needed) and the polyatomic ion’s name
Ex: Na2SO4
Na+
SO42-
2 x
1 xsodium sulfate
Examples
Fe(NO3)3 iron (III) nitrate
Mn(OH)2manganese (II) hydroxide
CuSO4copper (II) sulfate
Regents Chemistry
Revisiting the Periodic TableTrends of the Table
Properties of Elements
Trends to be familiar with: Ionization EnergyAtomic Radii Ionic RadiiElectronegativityReactivity of Elements
Summary of Trends
Ionization Energy – increases from left to right and up the columns
Atomic Radii – increases from right to left and down columns
Ionic Radii – depends on if the atom looses or gains electrons
Electronegativity – increases from left to right and up the columns
Reactivity – Groups 1,2 and 17 along with oxygen are most reactive
Families on the Table
3 – day website project: see handout