Year 10 Semester 1 Exam Flashcards
What is an Atom
Smallest part element can be broken down into
Consists of protons, neutrons, electrons
What is the Nucleus
Center of an Atom
Consists of Protons, Neutrons
High Density, Small Volume
Positively charged, holds 99.9% of mass
Mass of Proton
1 AMU
Mass of Neutron
1 AMU
Mass of Electron
1/200 AMU
AEZ Notation
Atomic Mass on top
Atomic Number on bottom
Element on side
How would an atom be neutral charge
If atom contains same number of protons & electrons
What is Electron Configuration
Way of writing amount of electrons in each shell
First shell takes 2 electrons
Second shell takes 8 electrons
Third shell takes 8 electrons
Fourth shell takes 8 electrons (Need to only know up to 2)
What Happens Across a Period
Across a period the size of the atom decreases
- As electrons are attracted more strongly to nucleus (More protons in nucleus)
- Chance of gaining electrons and forming negative ions increases
Period has same number of electron shells
What Happens Down A Group
Same number of valence electrons
- Group number tells us the charge and how many valence electrons it has
Form same number of bonds
Atoms get bigger down a group
- They hold their electrons less tightly (Even though they have more protons, there are more shells)
What Happens on Left Side of Periodic Table
Forms positive ions
As you go down group, forms ions easier, as the valence electrons are further from nucleus (More shells), so they let go of them easier (Francium is the weakest)
Postive ions are generally metals
What Happens on Right Side of Periodic Table
Forms negative ions
As you go to top of group, forms ions easier, as the valences are closer to nucleus (Less shells), so they can pull in more
Negative ions are generally non-metals
What is the Noble Gases Pattern
Noble gases unreactive
- Their outermost shell is always full (8 electrons, except Helium)
What is Electronegativity
Ability of an atom to attract additional electrons
As you go from left to right of periodic table, electronegativity increases
- Means the size of the atom gets smaller, increasing the attraction of electrons
- This is because the nucleus becomes more positive (Has more protons), pulling electrons in closer
As you go from up to down of periodic table, electronegativity decreases
Soluble Definition
Substance that can be dissolved
Insoluble Definition
Substance that cannot be dissolved
Solute Definition
Substance in solvent
Solvent Definition
Liquid that dissolves solute
Solution Definition
Mixture of solute & solvent
May be coloured, but always clear
Have uniform properties
Solubility Process of Ionic Compounds
1) Lattice structure of ionic bonds disrupted by water molecules
2) After dissolving, individual ions scattered throughout solution
What Happens When You Put Battery in Water
All positive ions go to negative electrode (Negative battery side)
All negative ions go to positive electrode (Positive battery side)
Precipitation Definition
Insoluble solution that can form as part of reaction between two ionic solutions
Solubility Definition
Ability for a solute to dissolve in a solvent to make a solution
Can use solubility table to check if compounds form solutions or precipitates
What is a Compound
Substance made up of 2 or more different elements in fixed ratio
What are Ionic Bonds
Metal with nearly empty outher shell reacts with non-metal with nearly full outer shell
Where the metal gives their electron to non-metal, so both get full shells
How Does the Lattice Structure in Ionic Bonding Work
Each ion in ionic compound is held in place by electrostatic attractive forces
- Held together as opposite ions attract (Anions & Cations)
Ions form crystal lattice made of ionic bonds
- Each positive ion surrounded by 6 negative ion, vice versa
- Keeps formation in place
What are Ionic Compounds
Compounds that consist of ions
Consists of metal and one or more non-metals
What are Properties of Ionic Compounds & Bonds
Conductive
Hard
High melting point & boiling point
Soluble
Brittle
- Force applied = Puts positive ions next to eachother, shattering the compound
–Due to repulsion of like charges
–Example: Salt (NaCl)
What is the Electrical Conductivity of Ionic Compounds in Solids
Ions in lattice are fixed in position
Don’t move = No charge flows
What is the Electrical Conductivity of Ionic Compounds in Liquids
Ions in lattice can move
Charge flows = Conducts electricity
Ions go towards their opposite charge (Positive to negative)
What are Covalent Bonds
Form when two non-metal atoms with nearly full outer shells share electrons
Neither one gives away an electron
- Shared electron count towards both atoms electron configuration
Diagrams mainly shown through electron dot diagrams
How are Covalent Bonds Formed
Non-Metals hold onto valence electrons
- Can’t give them away electrons to bond
- Though still need noble gas configuration
- They get it by sharing valence electrons with each other
– = Both atoms get to count electrons toward noble gas configuration
What do Covalent Bonds Make
Makes molecules
- Made by specific atoms joining together by sharing electrons
What Are the 2 Kinds of Molecules Formed by Covalent Bonds
Diatomic Molecules
Molecular Compounds
What are Molecular Compounds
Sharing electrons of different non-metals
Low melting & boiling points
Molecular formula shows type & number of atoms in molecule
- Not ratio, actual amount
- Doesn’t tell you how atoms arranged
What are Diatomic Molecules
Two of the same atom
Eg. Cl2, Br2
What are Diatomic Molecules
8 elements that always form molecules
Elements: Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Bromine, Iodine, Astatine
- All the -ogens, -ines
- Basically, Oxygen by itself means O2
Easy way to remember, 1 + 7 pattern on periodic table
What are the Types of Covalent Bonds
Single Covalent Bonds
Multiple Covalent Bonds
What are Single Covalent Bonds
Sharing of two valence electrons
Only non-metals & Hydrogen
Difference from ionic bond because they form molecules
- Two specific atoms joined
- In ionic solid, you can’t tell which atom electrons moved from/to
What are Multiple Covalent Bonds
Atoms that share more than one pair of valence electrons
- Double bond = Atom shares two pairs (4) of electrons
- Triple bond = Atom shares three pairs (6) of electrons
What are Metallic Bonds
Forms sea of mobile electrons throughout lattice structure
Aren’t held to any one ion
What is an Ion
Electrically charged, formed when atoms gain / lose electrons to fill shell
Fills shell to become more stable
Electrons that are gained by negative ions came from an ion
- That ion released an electron and became positive
What are Cations
If atom loses electrons to fill shell = Positive ion (Cation)
- Forms on left hand side of periodic table
Atoms that have few valence electrons that don’t attract as much, so they lose
What are Anions
If atom gains electron = Negative ion (Anion)
- Forms on right hand side of periodic table
Atoms with many valence electrons gain electrons forming negative ions
What are Ionic Substances
When an element from the left hand side joins with element from right hand side, the left hand side gives electron to right hand side
Naming Covalent Bonds
Element further left named first, keeps its normal name
- If two elements in same group, element further down named first
Element further right (Higher if in same group), named second
- End of its name changed to end in ‘-ide’
– Eg. Fluoride, Oxide, Sulfide, Bromide
Prefixes used to indicate if more than one element present in molecule
- 1 = Mono
- 2 = Di
- 3 = Tri
- 4 = Tetra
- 5 = Penta
Naming Ionic Bonds
Metal / Positive Ion named first
- Keeps normal name
Non-Metal / Negative Ion named second
- End of its name changed to end in ‘ide’
– Eg. Fluoride, Oxide, Sulfide, Bromide
Writing Formula For Ionic Compounds
Positive ion (Usually metal ion) written first
Negative ion (Usually non-metal ion) written second
Number of each ion adjusted so that positive charge = Negative charge
- Subscripts used to indicate number of ions present
– Shows ratio, not actual amount
- Use ‘drop and swap’ method
If non-metal or metal (Ammonium) has more than one element, than when ‘drop and’swap, put brackets around the one with multiple elements, as it is one ion
Writing Formula For Covalent Substances
Element further left named first
- If two elements in same group, element further down named first
Element further right (Higher if in same group), named second
Number of each ion adjusted so that charges are equal
- Subscripts used to indicate number of ions present
- Use ‘drop and swap’ method
What is an Acid
Substance that produces H+ ions in a solution
Has a pH of below 7
What is a Base
Substance that produces OH- ions in a solution
Has a pH of above 7
Metal Oxides and Metal Hydroxides are bases
Rate of Reaction Definition
How fast a reaction proceeds, does not mean more products are formed in reaction
How to Measure Rate of Reaction
Measures disappearance of reactant over time
Measures appearance of product over time
What is the Collision Theory
For reaction to occur, atoms/ions/molecules must collide with enough energy and correct orientation for reaction to occur
- Model known as collision theory
- Only some collisions result in reaction
Some collisions don’t result in reaction
- In these, the molecules bounce apart with no reaction
When it does result in reaction;
- A weak chemical bond forms between the new molecules
– Substance is unstable, and only exists for short period of time before it breaks apart
How to Increase Rate of Reactions By Nature of Reactants
Reactions are faster if there is an ion exchange (Ionic) and there is a formation of salts
Reactions are slower if there is a covalent bond formation between molecules, and when there are large molecules being formed
How to Increase Rate of Reactions By Surface Area of Particles Reacting
Breaking a piece into smaller pieces provides larger surface area on which reaction can occur
Powders have much larger surface areas than large-sized bits of material
- Surface area not size of pieces, but total area exposed to possible collusions
How to Increase Rate of Reactions By Increasing Concentration of Particles
In dilute solution, particles (molecules/ions) of reactant are spread out in solvent (Eg. Water)
- Lots space between reactant particles
In concentrated solution, there are more reactant particles in same volume, so they are closer together
In solutions with more particles, there are more collisions
- Therefore faster reaction rate
How to Increase Rate of Reactions by Increasing Temperature of Reactants
Particles in hot substances have more kinetic energy than particles in cold substance
- Particles in hot substance travels faster than particles in cold substance
Hot particles collide faster & more often than cold particles
- Higher amount of collisions + Greater energy = Greater proportion of collisions will result in reaction
–Because fast-moving molecules can push through repulsion of electrons that orbit atoms
– Therefore the electrons can orbit around different atom
– Faster the molecules, higher the proportion of reactants with enough energy to turn into products
How to Maintain Rate of Reaction
As reaction proceeds, particles of reactants get used up
- Fewer particles of reactants = Fewer collisions, therefore reaction rate slows
- To maintain reaction rate, products of reaction should be removed & replaced with particles of reactants
- To do this, just stir or mix reactants
What is a Catalyst
Substance that speeds up chemical reaction, but not used up in the reaction
How do Catalysts Work
Provide surface on which reaction can occur
Particles of reactants get absorbed (stuck onto) surface, where they react to form products
Products then released from surface of catalyst, freeing up catalyst to be used again
Other catalysts take part in initial reaction, and are regenerated in final reaction
What is the Nucleus
Membrane-enclosed organelle inside cell that contains chromosomes
They contain an array of holes/pores
What is the Ribosome
Is the site of protein synthesis in the cell
Ribosome reads messenger RNA sequence and translates into genetic code
What is the Purpose of DNA
Blueprint for controlling the characteristics of organisms
Each cell, except red blood cells contain DNA
What is the Structure of DNA
Double-Helix shape, like a ladder that has been twisted
Two strands of poly-nucleotide chains, attatched together by hydrogen bonds (Relatively weak bonds), between nitrogen bases
Two Vital Properties of DNA
Can make copies of itself, it two strands unwind, each strand can make new DNA molecule
Can carry information: Order of bases along strand is code for making proteins
What is the Structure of a Nucleotide
Nucleotide is complex molecule, made from three smaller molecules:
- A nitrogen base
- Sugar molecule (Deoxyribose)
- Phosphate Molecule
What is a Polynucleotide Chain
When nucleotides join together, they form a polynucleic chain called nucleic Acid
- DNA is two polynucleotide chains
- RNA is one polynucleotide chain
How are Nucleotides Joined Together
Nucleotides are joined together by sugar and phosphate groups
- Sugar of one nucleotide joins to phosphate of next nucleotide
– Sugar-Phopsphate backbone (Sides of a ladder)
What are the 4 Nitrogen Bases
4 Nitrogen Base Pairs:
- Adenine
- Thymine
- Guanine
- Cytosine
What is the Joining of Nitrogen Bases
Large base pairs always bond with small base pairs
- Adenine binds with Thymine
- Guanine binds with Cytosine
This is because it gives correct amount of space between strands
- Base pairs = Complementary bases
What is the Controversy of the Double Helix
James Watson and Francis Crick identified DNA as a double helix (Two-stranded spiral) in 1953
- They performed no experiments themselves, they interpreted experiment results from others
–One of them was Rosalind Franklin
In 1951, Rosalind Franklin started working in John Randall’s labratory in King’s College London
- When she was working, Maurice Wilkins (Another scientist working on DNA) was away
- Randall gave Franklin responsibility for her part in DNA project
When Maurice Wilkins returned, he thought Franklin was a technical assistant
- Not surprising, as the situation of women at university was not natural
Between 1951-1953, Rosalind Franklin became close to solving DNA structure
- Though was beaten to publication by Francis Crick and James Watson
- Was mainly because of dispute between Wilkins and Franklin
Wilkins showed Watson one of Franklin’s crystallographic images of DNA
- When James Watson saw picture, the solution became clear, and results were published in journal
- Franklin’s work was only a supporting article, making her contribution not acknowledged at the time
What are Chromosomes
X-Shaped objects found in nucleus of most cells
- Consists of long strands of substance called DNA
Every cell in body (Except red blood cells) have 46 chromosomes, or 23 chromosome pairs (Homologous)
- 23 from mother, 23 from father
What is the Location of Chromosome
Located in nucleus of cell
What is the Structure of Chromosome
Normally in X arrangements
Made up of DNA molecules tightly wound around proteins
What are Bivalent Chromosomes
‘X’ shaped chromosome
Two stands are identical to each other
Formed during DNA replication, so that two identical copies are produced
Each strand = Chromatid
Two chromatids are joined at Centromere
How Does DNA Fit In Cell
DNA fits inside cell because DNA molecules are tightly wound around small proteins called Histones
What is a Gene
- Section of DNA that has genetic code for making particular protein = Gene
Specific location has specific genetic code for making the protein
Humans have 1 billion codons, 3 billion nucleotides
Made from Nucleotides
How Does Genes Have Different Characteristics/Traits
As Chromosomes are made from DNA tightly wound around small proteins called Histones
- The order of nitrogen bases in each gene contains information for one characteristic/trait
– Eg. Gene may have information for making pigment melanin, giving us skin colour
– Eg. Gene may have information for making keratin for hair & nails
What Happens When Gene Needs to Make Proteins
When protein needs to be made, DNA in genes unwinds to make complementary base pairs copy called RNA
RNA can then leave nucleus through pores to make copy in cell’s cytoplasm (Protein Synthesis)
How Many Genes Does DNA Contain
DNA contains two genes (One from mother, one from father), for each characteristic
- Eg. Eye colour, Hair colour, etc.
What is a Codon
Sequences of 3 bases
Used to make proteins
What is a Karyotype
Is the complete set of chromosomes of an individual
- 46 total Chromosomes
- Is arranged from largest to smallest
What is Homologous Chromosomes
Pair of matching chomosomes
Chomosomes are organised into pairs, according to length & banding patterns
How Do Cells Change Into Various Roles
All complex organisms originated from single fertilised egg
Every cell in body started here, through cell division number of cells increased
Cell then specialise and change into various roles
What is Mitosis’ Purpose
Mitosis is to create new cells in the body that have been damaged or need to be replaced
What is Mitosis
Type of cell division where one parent cell divides to form two genetically identical daughter cells
- In humans, it means parents cells have 46 chromosomes, daughter cells each have 46 chromosomes
Most of the time, cells that are not dividing are in the phase - Interphase
- Where they do everyday processes (Eg. Making proteins)
Cells only start mitosis when new cells are needed
Every different type of cell in body contains same genes, but only some act to make cells specialise
Why is Mitosis Required
Esssential for organism to grow/repair damage
Body constantly undergoing mitosis & cytokenisis
Different types of cells live for different times
- But millions of your cells died and replaced as you read sentence
What are Somatic Cells
Somatic cells are all cells in body except for egg & sperm (Gamates)
- When somatic cells reproduce, they undergo mitosis
- Somatic cells are diploid (Carry two sets of genetic material - One from mother, one from father)
What is the Purpose of Meiosis
Meiosis is to produce gametes, or sex cells
Half of genetic material in each cell comes from mother, other half from father
What are Gamate Cells
Sex cell (Egg & Sperm) that has half genetic material of parent cell
- Male & Female gamates join to make form first cell of offspring
What are Haploid Cells
Only contains 23 chromosomes
Sperm cell has 23 chromosomes
Egg cell has 23 chromosomes
- When they combine at fertilisation, diploid somatic cell is produce
- One set of 23 chromosomes come from mother, another set of 23 chromosomes come from father
- Is why children are similiar, but not identical, to their parents
What is Meiosis
Process of cell division that produces haploid gametes
Two haploid gametes (One male, One female) combine to produce the first diploid cell of new organism
Type of cell division where number of chromosomes is halved
Occurs only when gametes are being made
What is Sexual Reproduction
Requires fusion of male & female gamates (Fertilisation)
- Each contains genetic information that influences offspring’s characteristics
22 pairs of human chromosomes are matching, but 23rd pair sometimes don’t match
- 23rd pair are sex chromosomes, determine whether you are male or female
What are 3 Factors That Can Create Variation in Sexual Reproduction
Independent Assortment of Chromosomes
Crossing Over to Mix & Match Chromosomes
Random Fertilisation
What is Independent Assortment of Chromosomes
Different organisations of chromosomes in sperm & egg after meiosis
- When cells are haploid, can go mother, father, father or father, father, mother, etc.
- 2^ 23 different combinations
What is Crossing Over to Mix & Match Chromosomes
Chromosomes overlap
- When separating, the tips of the chromosomes get mixed
- Creates variation
What is Random Fertilisation
Each sperm cell has equal chance of fertilising egg
If there was only 1 or 2 sperm cells able to fertilise, there wouldn’t be variation
- Since all have same chance, there is variation
If conditions could change, there could be variation of population, allowing some of them to survive
What is Mutation
Heritable change in structure or amount of genetic material
- Permanent change in DNA, may be in one gene or number of genes
Different Between Chromosomal and Genetic Mutations
If it affects single gene, it is a genetic mutation
- Causes alteration of nucleotide sequence of a gene
If it affects most of chromosome, it is a chromosomal mutation
- Causes structural change of the segment of chromosome
What Could a Tiny Change in Base Sequence Cause
Base sequence in DNA is critical
- Tiny change in sequence, changes order of amino acids in protein being made, which alters how protein functions
What Can Cause Mutation
Radiation
Chemicals
UV Light
Viruses
What is a Chromosomal Mutation
Failure of chromosome pair to separate at the centromere in meiosis
- Such case, one of daughter cells will have too many chromosomes, other will have too few chromosomes
How to Differentiate Between the Different Non-Disjunction Mutations
Down Syndrome
- Where person has 3 copies of Chromosome 21
Females With Turner’s Syndrome
- Where female has only one X chromosome
Males With Kleinfelter’s Syndrome
- Where males have 3 X chromosomes
What is a Genetic Mutation
A change in DNA
Where Does Meiosis Occur
In reproductive organs (Testes in Male, Ovum in Female)
Genetically Identical or Not Meiosis and Mitosis
Mitosis - Genetically Identical
Meiosis - Genetically Varied (Similiar)
Purpose of Karyotypes
Look for unusual changes in chromosomes
Check you and/or family for specific chromosome problems
