Chemistry Overview Flashcards
What is: an Atom
An atom is the smallest “unit” of matter that forms a chemical element. Everything is composed of neutral or ionized atoms.
What is: the number on the top left of an atom’s symbol
Atomic number
What does the Atomic number tell us
It tells us the position on the periodic table, the number of protons it has and it DEFINES the ELEMENT
What is: the number on the bottom left of an atom’s symbol
Atomic MASS number
What does the Atomic MASS number tell us
It tells us the number of protons & neutrons together
All elements have equal amounts of ________ and ________ so that they are NEUTRAL in CHARGE
Electrons & Protons. (All elements have equal amounts of electrons and protons so that they are NEUTRAL in CHARGE)
What charge does a proton have?
Positive charge
What charge does an electron have?
Negative charge
What charge does an Neutron have?
Neutral charge
What is the amount of Electrons allowed in each shell of an atom
2,8,8
Where in an atom do the electrons go
The electrons are on the shells of atoms
Where in an atom do the protons go
The protons go in the middle/center of an atom
Where in an atom do the neutrons go
The neutrons go in the middle/center of an atom
What is an electron arrangement
The number of electrons in each shell
What is the electron arrangement of Sodium (Na) HINT: It has 11 protons & hence 11 electrons and it has 23 protons and neutrons together therefore there are 12 neutrons
2,8,1
What is a ‘group’ on the periodic table
A vertical column
What is a ‘period’ on the periodic table
A horizontal column
How many shells will an element in ‘Period’ 3 have?
If it is in ‘Period’ 3 it will have 3 shells
How many electrons will be in the outer shell if an element is in ‘Group’ 2
If it is in ‘Group’ 2 it will have 2 electrons in the outer shell
What is: An ion
An ion is an atom or group of atoms with a charge (+ or -)
How does an atom become an ion?
An atom becomes an ion by GAINING or LOSING ELECTRONS in order to have a FULL OUTER/VALENCE SHELL in order to be STABLE.
Q1. What does the Lithium atom have to do to become an ion? Lithium has the electron arrangement of 2,1 and has 4 neutrons, 3 electrons and 3 protons.
Q2. What would the Lithium atom’s charge be if it lost 1 electron (negative charge) in order to become an ion?
A1. Since Lithium only has 1 electron in its outer shell it would be easier to lose 1 electron than gain 7 to have a full outer shell and therefore become stable.
A2. Since an electron has a negative charge and there are always the same amount of electrons and protons (- & +) in an atom there would now be 1 extra proton (+) than electron (-) so therefore it would have a positive charge of 1. And would look like this: Li⁺
What does Beryllium atom have to do to become an ion? Electron arrangement of 2,2
Beryllium would find it easier to lose 2 electrons (-) than gain 6 so therefore there would be 2 more protons (+) than electrons (-) so therefore the Beryllium ion would have a positive charge of 2 and would look like this: Be⁺⁺
What is the chemical formula for Aluminium Chloride
Al³⁺ + Cl¯ → AlCl₃
Cl¯
Cl¯
What is an ionic compound?
Formed from combining a POSITIVE and NEGATIVE ion. MUST be NEUTRAL in charge.
In a chemical reaction what always occurs:
REACTANTS → PRODUCTS
What are the three acids and what are their formulas
- hydrochloric acid= HCl
- sulfuric acid= H₂SO₄
- nitric acid= HNO₃
What is the only base and what is its formula
Any chemical with the HYDROXIDE ION is a BASE
- sodium hydroxide= NaOH
Any chemical with the HYDROXIDE ION is a BASE
How is a SALT formed
A SALT is formed from the metal ion of the BASE (sodium ion) plus an ion from an acid)
What does HYDROCHLORIC acid form
HYDROCHLORIC acid forms CHLORIDES
What acid forms CHLORIDES
HYDROCHLORIC acid
What does SULFURIC acid form
SULFURIC acid forms SULFATES
What acid forms SULFATES
SULFURIC acid
What does NITRIC acid form
NITRIC acid forms NITRATES
What acid forms NITRATES
NITRIC acid
What is the formula for the Carbonate ion
CO₃²¯
What is the formula for the Bicarbonate ion
HCO₃¯
How do elements become ions? Why?
An atom becomes an ion by GAINING or LOSING Electrons in order to have a full outer/valence shell in order to be stable.
Explain how oxygen becomes an ion?
Oxygen gains 2 electrons to become an ion. 8 electrons (negative), 8 protons (positive), electron arrangement 2,6. 10e (-), 8p (+) → O²¯: Oxide ion. Full valence/outer shell=STABLE, electron arrangement: 2,8
Give the formula for aluminium chloride and aluminium oxide, explain the number in each.
1) AlCl₃= Al³⁺ lost 3e (-), 10e (-) 13p (+)= 2,8=STABLE.
2) Cl¯ gained 1e (-). 17p (+) 18e (-)= 2,8,8=STABLE.
In Aluminium Chloride the 3 electrons lost from aluminium go to each chlorine atom to become a chloride ion (Cl¯). The compound is NEUTRAL in charge (the positive and negative ion combine because they are attracted to each other).
In a practical investigation what is the Aim (the given)
The aim is how TEMPERATURE/SURFACE AREA/CONCENTRATION effects the RATE of REACTION (how quick)
What is the INDEPENDENT VARIABLE? (It is something “you” decide to change) And what do you need to do with it?
TEMPERATURE/SURFACE AREA/CONCENTRATION. You need to decide what the independent variable is and how you will measure it. You must choose at least 4 variables within your Independent variable. Such as TEMPERATURE: 20°C, 30°C, 45°C & 70°C measured with a thermometer.
What is the DEPENDENT VARIABLE
What you measure as a result. How (from… until…) and with what…
What are CONTROL VARIABLES
What you keep the same. (Give values and how they are measured). REPEAT at least three times e.g trial 1, trial 2, trial 3.
What are the steps involved in a method for a practical investigation
- What you changed and how
- What are you measuring and how
- What are you keeping the same and how
- Repeats
- Any other relevant
How do you show your results
In a table label somewhere with time (s) and whatever the other variable is. Have it set out with the variables on the side and trial 1, 2, 3 and the average along the top. Draw a line graph.
How do you layout your line graph for a practical investigation
Time (s) is always on the vertical axis, then have the lowest of the variables on the left going up to the biggest. Only plot the averages. Start measuring from the very first line don’t start in a random place. Start from 0,0. Always have equal gaps between everything. Label the sides with the variable.
What is the CONCLUSION for a practical chemistry investigation
As TEMPERATURE/SURFACE AREA/CONCENTRATION INCREASES/DECREASES the TIME INCREASES/DECREASES hence the RATE of REACTION INCREASES/DECREASES. I know this because my average times for ____ was……, ____ was….., ____ was…. etc.
EXAMPLE:
As temperature increases the time decreases hence the rate of reaction increases. I know this because my average times for ____ was…, ____ was….., ____ was…. etc.
What are the steps involved in writing ACCURACY
- What were the control variable and what were they measured with…. why…..
e. g 2cm Mg strip measured with ruler because there was the SAME NUMBER OF PARTICLES in each trial. - 4mL of HCl measured with a measuring cylinder because there needs to be the same number of HCl PARTICLES in each trial. Draw measuring cylinder with a meniscus and arrow pointing out measured at eye level to avoid PARALLEX error and at the bottom of the MENISCUS (the curved part).
- The temperature was…. measured with a thermometer. This needs to be the same in order to have the same speed therefore the same kinetic energy.
- Concentration
- Surface area
Why do you measure liquids from the bottom of the meniscus?
To avoid PARALLEX error
What is the meniscus?
The curved part that you see if you look at a liquid at eye level.
How do you write up RELIABILITY in a chemistry practical investigation
- I measured the time with a stopwatch because it is a better instrument (more accurate and sensitive) than a clock.
- I used 5mL and 10mL measuring cylinders. They are more accurate and reliable compared to a beaker of larger measuring cylinder.
- I repeated each trial 3 times to eliminate any outliers and any other errors.