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Element Guide2Atomic Number: number of protons which is equal to the number of electronsHeElement Symbol4Atomic Mass Number = The number of protons + the number of neutrons.

The Periodic TableThe periodic table is a bit like a computer keyboard. Just as we combine the letters of the alphabet to make thousands of different words, many of the elements can join in different combinations to make millions of different substances.Group 1 Alkali MetalsGroup 1 metals are known as the alkali metalsGroup 1 metals include lithium, sodium and potassium..As you go DOWN Group 1, the alkali metals become more reactive - the valence (outermost) electron is more easily lost, because its further from the nucleus and more shielded from it by inner shells.

GroupsThe metals are most reactive in group I. They become less reactive moving towards the right. They also become more reactive moving down the table from top to bottom.The non-metals are most reactive in group VII. They become less reactive moving towards the left. They also become less reactive moving down the table from top to bottom.The noble gases (group VIII) are left out of this pattern because they do not react (inert).Elements in the same group react in similar ways.GROUPSThe columns in the periodic table are called groups. Groups of elements share similar reactivity.This is because they have the same number of valence electrons.

Group 1 are the alkali metalsGroup 7 HalogensGroup 8 Noble gases

6Group 1 stored under oil as they react with air,Reactivity increases because electrons are further from the nucleus so not held as tight ie easier to escape or reactPeriodsThe rows in the periodic table are called periods. Atoms size decreases from left to right in a given period

As you go left to right the added electrons only fill up a shell that already exists and so do not increase the size of the atom.but the electron cloud is pulled inward due to an increase in the nuclear charge (The more protons, the stronger the nuclear charge.)7Group 1 Alkali Metals1) The alkali metals all have ONE valence (outer most) electron. This makes them very reactive and gives them all similar properties2) They all have the following physical properties:Low melting and boiling points (compared with other metals)Low density Lithium, sodium and potassium float on waterVery soft can be cut with a knife3) The alkali metals always form ionic compounds. Group 1 Reaction with water Na + 2 H2O 2 NaOH + H2

Sodium + water sodium hydroxide + hydrogen

When group 1 are put in water, they react vigorously. The reactivity increases down the group the reaction with potassium gets hot enough to ignite itThey move around the surface, fizzing furiouslyThey produce hydrogenSodium and potassium melt in the heat of the reactionThey form a hydroxide in solution, i.e. aqueous OH ions

Group 7 - Halogens

Group 7 is made up of fluorine, chlorine, bromine, iodine and astatine.All group 7 elements have seven electrons in their outer shells (valence electrons) so they have got similar properties.As you go DOWN Group 7, the halogens become LESS reactive - theres less force to pull the extra electron in when its further away from the nucleus and more shielding electronsGroup 7 Halogens

Chlorine is a fairly reactive, poisonous, dense green gasBromine is a dense, poisonous orange liquidIodine is a dark grey crystalline solidHalogens can either form ionic or covalent compounds

Pics?Group 7 HalogensHalogens react with alkali metals to form saltsThey react vigorously with alkali metals to form salts called metal halidesMore reactive halogen will displace less reactive onePics?2Na + Cl2 2NaCl2K + Br2 2KBrCl2 + 2KI 2KCl + I2 Cl2 + 2KBr 2KCl + Br2 I2 + KCl No reactionBr2 + 2KCl No reactionDiatomic MoleculesThese seven elements occur naturally as molecules containing two atoms.

14Electron ConfigurationThe octet rule states that atoms are most stable when they have a full shell of electrons in the outside electron ring.

On the Periodic Chart with shell totals you can easily see the octet rule. A valence is a likely charge on an element ion.

All of the Group 1 elements have one electron in the outside shell and they all have a valence of plus one. Group 1 elements will lose one and only one electron, that single outside electron to become a single positive ion with a full electron shell of eight electrons (an octet)

Group 2 elements all have two electrons in the outer shell and all have a valence of plus two. Group 2 elements lose two electrons to become +2 ions. They do not lose only one electron, but two or none.

The Transition Elements, Lanthanides, and Actinides are all metals. Many of them have varying valences. For this reason they sometimes appear to violate the octet rule.

Group 3 elements have a valence of plus three. Boron is a bit of an exception to this because it is so small it tends to bond covalently. Aluminium has a valence of +3, but some of the larger Group 3 elements have more than one valence.

The smallest Group 4 elements, carbon and silicon, are non-metals because the four electrons are difficult to lose the entire four electrons in the outer shell. Small Group 4 elements tend to make only covalent bonds, sharing electrons. Larger Group 4 elements have more than one valence, usually including +4.

Small Group 5 elements, nitrogen and phosphorus, are non-metals. They tend to either gain three electrons to make an octet or bond covalently. The larger Group 5 elements have more metallic character.

Small Group 6 elements, oxygen and sulphur, tend to either gain two electrons or bond covalently. The larger Group 6 elements have more metallic character.

Group 7 elements all have seven electrons in the outer shell and either gain one electron to become a -1 ion or they make one covalent bond. The Group 7 elements are diatomic gases due to the strong tendency to bond to each other with a covalent bond.

All of the inert elements, the noble gases, have a full octet in the outside shell (or two in the first shell) and so do not naturally combine chemically with other elements.

Electron ConfigurationElectrons are are arranged in shells around the nucleus. Each shell is a different energy level.The first shell fits up to

The second fits up to

The third fits up to

So the electron shell arrangement for 12Mg would be2 e8 e18 eInteractive periodic table2, 8, 223Write on board Li (2,1) Ca (2,8,8,2) P (2,8,5) they need to write the electron arrangement Then 2,8,7 (Cl), 2,6 (O) 2,8,1(Na)

Chemical BondsAll atoms want to be like the noble gases.Noble gases have all the electrons they need to fill their outer shell. Atoms react with other atoms so they can fill their outer shells with the right amount of electrons (we will say that is the magic number 8). This is called covalent bonding where atoms share electrons to achieve their full complement.Ionic bonds are between a metal and non-metal and involves the gain and loss of electrons.Ions, Ionic bonding & Naming Ionic CompoundsIonsWhen atoms lose or gain electrons, they become ions.___________ are positive and are formed by elements on the left side of the periodic chart.____________ are negative and are formed by elements on the right side of the periodic chart.

26Ions

IONS are atoms or groups of atoms with a positive or negative charge. ___________ an electron from an atom gives a CATION with a positive charge__________ an electron to an atom gives an ANION with a negative charge.To tell the difference between an atom and an ion, look to see if there is a charge in the superscript! Examples: Na+ Ca+2 I- O-2 Na Ca I OIonic Bonds____________ (such as NaCl) are generally formed between metals and nonmetals.

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Common Cations

30Common Anions

31Forming Cations & AnionsA CATION forms when an atom ______ one or more electrons.An ANION forms when an atom ______ one or more electronsMg ______--> Mg2+F + e- --> ____PREDICTING ION CHARGESIn generalmetals (Mg) _____ electrons ---> cationsnonmetals (F) ______ electrons ---> anionsWriting FormulasBecause compounds are electrically neutral, one can determine the formula of a compound this way:The charge on the cation becomes the subscript on the anion.The charge on the anion becomes the subscript on the cation.If these subscripts are not in the lowest whole-number ratio, divide them by the greatest common factor.

34Learning Check CountingState the number of protons, neutrons, and electrons in each of these ions. 39 K+ 16O -241Ca +2 198 20#p+ ___________________ #no ___________________#e- ___________________

One Last Learning CheckWrite the nuclear symbol form for the following atoms or ions:

A. 8 p+, 8 n, 8 e-___________

B.17p+, 20n, 17e-___________C. 47p+, 60 n, 46 e-___________ Charges on Common Ions

-1-2-3+1+2By losing or gaining e-, atom has same number of e-s as nearest Group 8A atom.IonsAtoms have an overall neutral charge because the number of protons ______ the number of electrons.An ion is an atom that has gained or lost one or more electrons.Positive ions are atoms that have _____ electrons.Negative ions are atoms that have ______ electrons. ThinkingWhat is the difference between an atom and an ion?List the 3 particles in an atom and their electrical charges.Which particles in an atom determine its atomic number?Explain why the sodium ion carries a positive charge.Ionic CompoundsThe ions that have been formed are now ________ to oppositely charged ions.So Mg2+ will be attracted to Cl-. This forms an ionic compound.Some ionic compounds are soluble others are insoluble.Compounds which are insoluble form solids called precipitates.40Expt make smurf snot and ppt on spotting tilesDifficult IonsIonsNameNO3-CO32-HCO3-OH-SO42-S2-NH4+PO43-Ionic BondingNa+ Cl

2,8,1

2,8,7Na+Cl-2,82,8,8How do these atoms become stable? Ions are formed by gaining or losing electronsRemember the number of protons and neutrons doesnt change so if you take electrons the ion formed is positiveWhat does the atomic model look like for each?What is the numerical electron configuration for each? 281 and 287How many electrons in 3rd energy level (outer shell) of Na?How many electrons in 3rd energy level of Cl?What is the easiest way for each to get a full outer shell?Na donates electron to Cl to form ionsIn Na ion positive or negative? And Cl Opposites attract. new compound NaCl pg 164 crystal latticeWhat about MgCl2, ZnO, MgO, KIDS cut out ion flashcards H/O and find partners to bond withIONIC FORMULAESo Mg2+ will be attracted to Cl-.Because Mg is 2+ and Cl is only 1-, Mg will attract 2 Cls.The compound formed will be ______.The subscript shows that they are 2 Cls for each Mg.If the starting ions were Cu2+ and S2-, the 2 ions have the same charge. So each Cu will only attract 1 S. The compound formed will be ______.There is never any charges on the final product - they balance out43If mg is 2+ how many cl- ions will it attract?Create ionic compounds for Na+Cl-(NaCl), Li+ S2-(Li2S) Al3+I-(AlI3) what about Fe3+o2- (Fe2(o)3 Why swap and drop try Al3+ so42- Al2(So4)3 and mg2+ po43- (Mg3(po4)2Covalent CompoundsThe subscript to the right of the symbol of an element tells the number of atoms of that element in one molecule of the compound.

44Types of FormulasEmpirical formulas give the lowest whole-number ratio of atoms of each element in a compound.Molecular formulas give the exact number of atoms of each element in a compound.

Example: glucose C6H12O645Types of FormulasStructural formulas show the order in which atoms are bonded.Perspective drawings also show the three-dimensional array of atoms in a compound.

46Nomenclature47Learning Check A. Element in Group XVII, Period 4 1) Br2) Cl3) Mn

B. Element in Group II, Period 3 1) beryllium2) magnesium 3) boron