WEEK 1: Chemical Level of Organisation Flashcards
(79 cards)
What is matter made up of
- made up of atoms
What do atoms do? what are they made of
- join together to form chemicals with different characteristics
- subatomic particles
What are 3 subatomic particles, THEIR UNIT AND MASS
PROTONS
-> positive charge, 1 mass unit
NEUTRONS
-> neutral 1 mass unit
ELECTRONS
-> negative charge, low mass
Describe the atomic structure
- atoms contain equal number of protons and electrons
- nucleus contains protons and neutrons
- contains an electrical cloud: spherical area that contains electrons, no of electrons determine the reactivity of atom, and electron shell(Size)
What is a valence shell
- the outer occupied shell
- they hold electrons at a higher energy
What is an atomic number
number of protons in an atom
What is an element?
pure substance composed of atoms of one kind
what is an isotope
atoms with same no of protons but diff no of neutrons
What is an isotope mass number
- no of protons plus no. of neutrons
What is an atomic weight?
- avg of the diff atomic masses and proportions of diff isotopes
Describe the arrangement of electrons in electron shells
- electron cloud contain shells/ or energy levels
- first energy level hold max 2 electrons
- 2nd + 3rd energy levels can hold max 8 electrons
What is a chemical bond
- involves sharing, gaining an dlosing electrons
What is a molecule
- 2 or more atoms joined by a strong chemical bond
what is a compound
- 2 or more atoms of diff element joined by strong or weak chemical bonds
What are the 3 major types of chemical bonds
- ionic bonds
- covalent bonds
- hydrogen bonds
What are ionic bonds?
- an atom w an electric charge
- indicated by a plus or minus following an element eg Na+
- atom (elecr donor) loses on or more electrons = cation indicated by (+) sign
- atom (elec acceptor) gains the same electrons = anion indicated by minus
- are attractions between cations (+ions) and anions (-ions)
- eg Na gives up up an electron which is gained by Cl-> opposite charged = ionic compound NaCl
What are covalent bonds
- electron donated by each atom to make pair of electrons
- sharing 1 pair = single covalent bond
- sharing 2 pairs = double covalent bond
- sharing 3 pairs = tripled covalent bond
How many bonds does carbon, hydrogen, oxygen and nitrogen make in molecules
4,1,2,3
What are non polar covalent bonds
- equal sharing of electrons between atoms that have equal pull on electrons
- cannot form hydrogen bonds
What are polar covalent bonds
- unequal sharing of electrons because one atom has a disproportionately strong pull on electrons
- form polar molecules eg water as O atom hold electrons more tightly, 2 extra electrons= slight neg charge = H atoms weakly positive
What are hydrogen bonds
- weak polar bonds between adjacent molecules based on electrical atractions
- involves attraction between slightly + charge and a slightly - charge.
- they form between water molecules
What is the electronegativity for oxygen, nitrogen , carbon, hydrogen
3.5 = oxygen
3.0 = nitrogen
2.5 = carbon
2.1= hydrogen
What are reactants and products?
- r:materials going into a reaction
- p:materials coming out of a reaction
What is kinetic, potential, chemical energy?
- energy of motion
- stored energy
- potential energy stored in chemical bonds