SC10 - Chemistry unit test

99\.9% of mass of atoms are from what 2 ?

\-protons

\-neutrons

how to find # of neutrons in atom?

atomic mass - atomic # (# of protons) =

what does bohr model show

\-# of electrons in each shell

why are noble gases stable?

filled valence shells

\-doesn’t gain or lose

how do atoms form ions?

\-it has gained or lost electrons

\-ion charge # = amount to be restored to original

pos ion vs neg ion

\-more of what

\-name

pos ion = more protons than electrons

neg ion = more electrons than protons

——

cation = pos

anion = neg

\-metals tend to (gain/lose) electrons

\-non mentals tend to (gain/lose) electrons

\-metals lose electrons → form pos ion

\-non-metals gain electrons → form neg ion

compound

pure substance made up of 2 or more types of atoms

how do ionic compound form

\-r they charged or neutral

electrons transfers

\-neutral cuz transfers to GET full valence shell

ionic lattice

repeating pattern of pos and neg ions in compound

how do covalent compounds form

each atom shares electron(s)

what are molecules

covalent compound

\-neutral (ions have charge so can’t be)

polyatomic ion

\-are bonded how?

\-why ion?

\-covalently bond

\-has charge

4th orbit max. of # electrons

18

what parts of atom participate in forming chemical bonds? (be specific

VALENCE electrons

lewis diagram only ___ is shown

\-how do you draw electrons? what side first?

valence electrons

\-dots → place in singles until 5th, then pair.

\-east then counter-clock

how to draw ionic bonds in lewis dot diagram

→ use __ on outside

→ what’s written on out-est part?

→ transfers by GAINS to get full valence shell

→ transfers by LOSS to get full valence shell

→ brackets

→ pos/neg ion charge

→ no dots

→ all dots

how to draw covalent lewis dot diagram

→ non-bond pair

→ bonding pair

\-dots (2)

\-line

is oxygen a molecule

yes → 2 or more atoms bonded covalently

what is true about elements in a period

sideways

\-same # of energy shells

what’s a metalloid

both properties of metal + non-metal

why doesn’t noble gas have ions?

already full valence shell

things to know when NAMING ionic compounds (4)

\-first is always positive ion

\-last is always neg ion

\-last needs **ide** ending

\-if multivalvent (many ions), use roman numeral for ion

how to write ionic formula (criss-cross)

\-write ion charge as superscript of element

\-criss cross and drop to subscript

\-simplify

how is subscript different in ionic + covalent compounds ?

ionic → can simplify

compound → CANNOT simplify → needs actual amount

how to name covalent compounds (

\-NEED PREFIXES to show # of atoms in element (except if first is 1/no mono in front)

\-need **ide** ending

exception to prefixes

\-first one is only 1 atom / no mono in front

law of conservation of mass

* matter is not created or destroyed
* total energy in closed, isolated system remains constant

\-just rearranged

\-same mass + # of atoms

states of matter

(aq)

(s)

(l)

(g)

\-aqueous / dissolved in water

\-solid

\-liquid

\-gas

diatomic elements (7)

Hydrogen

Nitrogen

Fluorine

Oxygen

Iodine

Chlorine

Bromine

open vs closed system

→ these example of what

open : things (ex. gas) can escape SO mass will decrease

close: NOTHING escapes SO mass same

\
ex. of law of conservation cuz escaped stuff has mass

classify types of chemical reactions (6

1. synthesis
2. decomposition
3. single replacement
4. double replacement
5. neutralization
6. combustion

synthesis

2 reactants → 1 product

ex. A + B → AB

decomposition

1 reactant → 2 (or more) products

ex. AB → A + B

single replacement

\*thing to note

1 element switches with (metal/non-metal) element from compound

→ if metal, switch w/ first

→ if non-metal, switch w/ back

ex. A + BX → B + AX (metal

double replacement

swap elements so 2 NEW compounds

\-front (metal) stays first

\-back (non-metal) stays back

ex. AB + CD → AD + CB

neutralization

acid + base → salt + water

ex. HA + BOH → AB + HOH

how can tell if smth is acid/base + needs neutralization

acid → will have H

base → will have OH

neutralization is a special case of what other kind of reaction

double replacement

ex. **H**A + B**OH** → AB + **HOH**

combustion

element/compound react w/ oxygen and makes an oxide

ex. C,H, + O2 → CO2 + H2O

pH scale

\-below 7

\-7

\-above 7

numbered scale of strength of acid + base

\-acid

\-neutral

\-base

how much more acidic is 3 from 6?

10^3 = 1000

10^(6-3) = 1000

methyl orange

3\.2-4.4

red to yellow

methyl red

4\.8-6.0

red to yellow

bromothymol blue

6\.0-7.6

yellow to blue

litmus (red)

7

red to blue

phenolphthalein

8\.2 - 10

colourless to pink

indigo carmine

11\.2 - 13

blue to yellow

pH meter

uses electrical probes to measure how solutions conduct electricity

acids/base only behave OR has properties like acid/base when….

dissolved in water

has (aq) symbol

naming acids

\-start with..

\-ending with..

\-start with H → hydro…

\-take away **ide** ending, replace with …**ic**

acids/base can _____ _______ bc they release ions

\-acid release what

\-base release what

conduct electricity

* H+


* OH-

can solution have both acid (high H+) and base (high OH-)?

why or why not

NOOOO

cuz they will balance to form neutral (water)

basically neutralization

properties of acid

\-taste 

\-touch 

\-reaction w/ metals 

\-conduct electricity 

\-sour

\-many burns skin

\-yes, corrodes

\-yes

properties of base

\-taste

\-touch

\-reaction w/ metals

\-conduct electricity

\-bitter, soapy

\-slipper, soapy, many burns skin

\-no

\-yes

salt is another name for WHAT

ionic compound

\-metal and non-metal

why is ocean acidic

burning fuel

= carbon dioxide gas

= co2 react with water

= forms carbonic acid (H2CO3)

how does adding excess carbon dioxide gas = shellfish cant make shells

→ excess carbon dioxide react w/ water

→ forms carbonic acid

→ needs carbonate ions (BASIC) to neutralize it = less carbonate ions

= lower carbonate level

= shellfish needs carbonate ions to make shell but not many ;(

→ specifically need calcium carbonate (formed by carbonate ions)

what energy is stored in the bonds between atoms in compound

potential energy

closed vs isolated system (HMMMMM)

\-closed system CANNOT exchange mass, ONLY

\-isolated system CANNOT exchange energy OR mass

total energy in system is…

potential + kinetic energy

break bonds

\-what energy

\-exo / endo

\-absorb energy

\-endothermic

form bonds

\-what energy

\-exo/endo

\-release energy

\-exo

solid precipitate is formed

what change is it (phys or chem)

chemical :o

activation energy def

\-comes from where

\-ex.

**minimum amount** of energy required to **break bonds** in reactants to start reaction

aka jumpstart

\-comes from surrounding

\-ex. spark or lit match

endothermic reaction

\-**system** is colder? or hotter?

soooooo?

\-system is colder

sooooo

need to ABSORB energy from surrounding

exothermic reaction

\-**system** is colder? or hotter?

soooooo?

\-system is hotter

sooooo

need to RELEASE energy to surrounding

\-is freezing endo or exo → going up

\-is melting ice endo or exo → going down

\-exo → release heat out of water to freeze

\-endo → absorb heat into ice to melt

name 3 household acids + pH value

name 3 household bases + pH value

acid

\-lemon → 2

\-tomato → 4

\-milk → 6

\
base

\-egg → 8

\-soap → 10

\-beach → 12

overall energy change is …

difference of reactants + products