Level 10 Science

Instructions for Note Taking -Take Cornell notes on this powerpoint - Notes must be in own words with individual commentary - Include a well written summary at the end of the notes

Terms Atoms are the basic particles of elements A compounds is made of two or more different elements Atoms combine to make particles of a substance: molecules and ionic compounds Molecules: Association between two or more atoms with a covalent bond Ionic compounds: Formed between two or more atoms with an ionic bond

Terms continued Chemical Reaction: process in which the atoms of substances (reactants) rearrange to form new substances (products) Example? Atoms are not created or destroyed during chemical reactions, only rearranged Acids can be neutralized during reactions

In this unit, we will… Use atom tiles to model rearrangement of atoms during reactions Use chemical forumals and equations to represent chemical reactions Perform a lab with limewater, hydrochloric acid, and sodium bicarbonate Conduct a neutralization reaction

Compound A compound is a substance consisting of two or more atoms that are bonded together Cannot be separated by physical means Five bonds we will learn about: ionic bonds, covalent bonds, polar covalent bonds, hydrogen bonds, and metallic bonds

Electrons have a role in bonding Bohr Model Flourine example Bohr model shows simple circular electron levels Also called electron configuration How many electrons can each level hold?

Electron dot configuration Just like the Bohr model, but only shows the valence electrons 1 dot on each of the 4 sides Go around a place a 2 nd dot on the 4 sides until you run out of valence electrons

Electrons role in bonding continued When atoms react with one another, they will gain, lose, or share an electron from their outermost level What is this electron called? The number of electrons they gain, lose or share determines their reactivity Reactivity describes how likely an element is to form bonds with other elements

Ions It will have a charge of +1, which makes it a cation (ion with a positive charge) When chlorine gains sodium’s extra valence electron, what charge will it have? It will have a charge of -1, which makes it an anion (ion with a negative charge)

Common Cations and Anions chem anions of groups 567.pdf N -3 P -3 As -3 O -2 S -2 Se -2 Te -2 F -1 Cl -1 Br -1 I -1 chem cations of groups 1 and 2.pdf Li +1 Na +1 K +1 Rb +1 Cs +1 Fr +1 Be +2 Mg +2 Ca +2 Sr +2 Ba +2 Ra +2

Ionic bonds Bonds formed by the transfer of electrons from one atom to another When forming bonds, most atoms want to have 8 electrons in their outer layer If they have 5 valence electrons already, how many do they want to add? If they have 7 valence electrons already, how many do they want to add? Which group, 5 or 7, is more likely to form a bond (more reactive)?

Ionic bonds continued Sodium ion has 1 valence electron Chlorine has 7 valence electrons Chlorine wants one more, and sodium has one to give

Ionic bonding continued When sodium gives up its 1 valence electron, what charge will it have? Sodium and chlorine are now oppositely charged ions, so they will attract each other forming the compound NaCl, or table salt

Ionic bonds continued Magnesium is in group 2, so it has 2 valence electrons Magnesium can also bond with chlorine But Chlorine only needs 1 more electron What do you do with the other valence electron from magnesium? Add 2 chlorines! 2 chlorines need 2 valence electrons total, and magnesium has 2 to give!

Covalent Bonds Bonds formed when the atoms share valence electrons Likely to form between atoms that have four, five, six or seven valence electrons Group 4 needs 4 valence electrons to make 8, so they share 4 of their electrons with other atoms Group 6 needs 2 more electrons to be stable, so they share __ of their electrons with other atoms

Molecules and Covalent Bonding Atoms held together by covalent bonds form a MOLECULE A covalent bond shares one pair of electrons water ammonia

Single, Double, and Triple Covalent Bonds Single Bond- one pair of electrons shared Double bond- two pairs shared Triple bond- three pairs shared

Summary Electrons have a role in bonding Bohr model and electron dot configuration Chemical Reaction: occurs when atoms rearrange to form new atoms Ionic bonds- electrons are transferred Cations- positive ions, anions- negative ions Covalent bonds- electrons are shared Called molecules Can be single, double or triple bonds

Quiz 1. Draw an example of a compound 2. What is an ionic bond? 3. In what groups does an ionic bond occur? 4. What is a covalent bond? 5. In what groups does an covalent bond occur?