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biology summary (english)
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summary of biology, in full English. There are no photos in it? but I personally put the book on the side. This just worked flawlessly.
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Chapter 1: the chemistry of living things,1.1 all matter consists of elements
Element
= fundamental (pure) form of matter that cannot be broken down to a simpler form
Periodic table of elements:
- 188 elements
- Arranged in columns & rows based on their similar properties
Elements are made up of atoms:
Atom
= smallest unit of any element that still retains the physical & chemical properties of element
- Living & non-living
- Smallest functional units of matter
- Split apart in unusual circumstances (nuclear reaction)
Nucleus
= central core of an atom
- Made up of positively charged particles (protons)
- And neutral particles (neutrons)
-> atomic number (number of protons)
-> atomic mass (number of protons & neutrons)
Electrons
= smaller negatively charged particles (orbit nucleus)
- Constantly moving, precise position is unknown
- “clouds” of negative charge around nucleus
- “clouds” = shells
- Each shell certain number of electrons
- first shell: 2 electrons
- second shell: 8 electrons
- third shell: 8 electrons (sometimes no third shell)
- Each atom unique number of electrons
- Normally same amount as protons
-> result: atom is electrically neutral
- Protons & neutrons => same mass (more mass than electrons)
,-> 99,9% of the atoms mass (neutrons & protons)
Subscript numeral
- O₂ = 2 oxygen atoms linked
- H2O = 2 hydrogen atoms & 1 oxygen atom linked
Isotopes
= atoms with more or fewer neutrons then the normal number for that element
- Same atomic number
- Different atomic mass
- Superscript mass number => 14C (Carbon-14)
- unstable
- Radioisotopes = give of particles & energy (radiation) to reach stable state
-> can damage tissues
-> scientific & medical uses
-> use: “tag” molecules so they can track location
Free radical
= atom or molecule has one or more unpaired electrons in outer shell, independent existence
- Highly reactive (taking or giving electrons to or from other molecules)
- Small amounts produced by metabolic processes (toxic waste)
- Damage biologically important molecules (like DNA or proteins)
1.2 Atoms combine to from molecules
Molecules join together is about energy
Energy
= capacity to do work
- Potential energy = stored energy, not preforming any work (still water)
- stored in bonds that hold atoms together in all matter, living & non-living
- when bonds break: potential => kinetic
- Kinetic energy = energy in motion, preforming work (flowing water)
- Used for: breathing, digesting & moving
- Electrons are attracted to positive charged nucleus & repelled by each other
- Electron moves closer to nucleus => loses energy
- Electron moves further from nucleus => absorbs energy
, Atoms most stable when outermost shell is fully filled with electrons
- Interaction with other atoms to fill shell
- Chemical bonds = when atoms are bound to each other
- 3 types of bonds:
1. Covalent bonds (electron-sharing-bond)
- sharing a pair of electrons
- H --- H (structural formula)
- Single bond = sharing one pair of electrons
- Double bond = sharing two pairs of electrons (O === O)
- Strong bond
2. Ionic bonds
− giving up or taking electrons
− loss or gain gives atom net charge
− ion = electrically charged atom
− ionic bond = 2 oppositely charged ions come together
− electrolytes = ions in aqueous solutions
− Moderate bond
-> good conductors of electricity
3. Hydrogen bonds
− Molecules without net charge
− Sharing is unequal
− Uneven sharing => partial negative & partial positive charge
− Polar molecules = molecules are electrically neutral but partially charged poles
− Negative & positive pole are oriented towards each other
− Weak bond
6 important elements:
1. Oxygen (O)
2. Carbon (C)
3. Hydrogen (H)
4. Nitrogen (N)
5. Calcium (Ca)
6. Phosphorus (P)
-> most stable and can combine with other elements
Matter is most stable when it contains least amount of potential energy
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