Structure of Atoms
What is an atom? What does an atom consist of?
Buildin block of all matter
Nucleus ( protons + neutrons)
Electrons
What are endothermic and exothermic reactions? (related to conservation of mass)
Endothermic- rection that absorbs energy ex.combustion
Exothermic- reaction thar releases energy ex. photosynthesis
What are the 3 chemical bonds?
Ionic, covalent and metallic
Who created the atomic theory of the universe?
What did Niels Bohr discover?
Electrons absorb energy and get excited, they glow when they lose energy. Explain about electron shellls
How is the periodic table arranged? (group, period...)
The period number represents the number of electron shells in the element
The group number represents the number of electrons in the outer shell (valence electrons arranged 2,8,8: K,L,M).
What is a chemical reaction?
A process where 1 set of chemical substance is transformed into another set of chemical substance. A chemical reaction is accompanied by energy change and transformed through the rearrangement of atoms.
What is metallic bonding?
Atoms are held together by metallic bonding. Electrons flow in a sea of free electrons - reason why metals are malleable. Metals have relatively few electrons.
What was lavoisier's discovery?
Discovery of conservation of mass.
Discovery of elements H,O.
CH4 + 2O2
CO2 + 2H2O
What is an isotope?
atoms of the same number of protons (Z) but different mass number (A)
Extra: they have the same chemical properties as elements but different physical properties
What is the law of conservation of mass?
Matter is conserved, it is neither created nor destroyed. Mass of matter is always the same.
Energy is conserved - stored w chemical bonds.
What is ionic bonding? What happens during ionic bonding?
Ionic bonding happens between a metal and a nonmetal. A metal loses a velence electron(cation)and the non metal gains an electron(anion).
EXTRA:Strong electrostatic attraction - high metling point
What was the law of proportions?
Dalton's theory which led to atomic theory that elements combine in certain ratios.
C3H8 + 5O2
3CO2 + 4H2O
What does an element consist of? What do (A) and (Z) signify?
A unique atomic number (Z) - number of protons
A unique chemical sign
A mass number (A) - Z + no. of neutrons
What is covalent bonding? What is the OCTET rule?
When atoms shair electron pairs. All molecules are covalent.
OCTET rule = atoms in a covalent bond tend to have a full outer shell
What is the plum pudding model?
Thomson's theory that most of the atom is a positive pudding with negative plum pieces. Placed a glowing beam between high voltage electrons and realised that atomes consist of charged particles.
H3PO4 + 3NaOH
3H2O + Na3PO4
What is an element, molecule and compound?
Element - substance containing only 1 type of atom
Molecule - neutral group of 2 + atoms, held together by chemical bond
Compound - molecules made up of 2 + elements
What was Rutherford's theory? How did he find it out?
His theory was that an atom consists of a small positive nucleus. He discovered it with alpha particles deflecting light instead of continuing straight.