Atomic structure
Explain Dalton's theory
Atoms can't be destroyed, created or subdivided. Elements are made of extremely small particles called atoms
Explain cations and anions
Cations are positively charged, lose electrons to obtain a stable outer shell. Groups 1-13 metals, generally charged +1, +2.
Anions are negatively charged, gain electrons to obtain a stable outer shell. Groups 15-17 non metals, charged -3, -2, -1.
Which of the following is an example of a physical change, not a chemical change?
A) rusting of ice
B) Burning of wood
C) Melting of ice
D) Cooking an egg
C, melting of ice
1-How do you convert from molecule/atoms/particle to mol/mole?
2-How do you convert from mole to molecule?
1- Molecule: 6,02. 10^ 23
2-
Explain Plum Pudding model
A positively charged sphere with negatively electrified little parts
Alkali metals
Alkaline earth metals
Elements in group 1. Form +1 cations by losing their single valence electron, form ionic compounds.
Elements in group 2. Form +2 cations by losing 2 valence electrons, form ionic compounds.
How do you separate a mixture of sand and salt?
A) Distillation
B) Filtration and evaporation
C)Chromatography
D) Decanting
B, filtration and evaporation, add water, filter and evaporate
Explain Rutherford model
On the nucleus, protons and neutrons, and electrons move around the nucleus in circular orbits. Also, the nucleus and electrons are held together by electrostatic forces.
Halogens
Noble gases
Elements in group 17. Form -1 anions by gaining one electron, form ionic compounds with metals, form covalent compounds with nonmetals.
Elements in group 18. Full valence shell and stable, difficult to remove electrons and gain.
Phase change that goes from solid to gas
Sublimation, from solid to gas
Explain Bohr model
Electrons move in specific orbits/energy levels around the nucleus.
Metals
Nonmetals
Metalloids
Metals= groups 1-12 (3-12 are transition metals) and part of 13-16 (Al -Fl are post transition metals). Tend to lose electrons to form cations.
Nonmetals= groups upper right corner 14-18 and hydrogen. Tend to gain electrons to form anions or covalent bonds.
Metalloids= staircase from B to Po, can form cations or anions.
Type of matter that has a fixed composition and can't be separated by physical means
Element, they are pure substances
1-What the atomic number means?
2-Explain isotopes.
3-What is the mass of an isotope?
1- The atomic number means the number of protons
2- Isotopes are atoms of the same element but with different masses and neutrons.
3) Mass= protons+ neutrons
Which of the following is most likely to form a +2 cation in an ionic compound? And why?
A)Na
B) Mg
C) Al
D) F
B) Mg, it loses 2 valence electrons to achieve stable electron configuration.
A phase change that a substance release energy to its surroundings
Freezing releases energy.