Flashcard: Introduction to Atomic and Periodic Chemistry — 40 carte

Atomic nucleus — contents?

Protons and neutrons.

Isotopes — same?

Same element, different neutrons.

Mass number — sum?

Protons plus neutrons.

Atomic number — equals?

Number of protons.

Electron count — in a neutral atom?

Equal to protons.

Periodic table — group number?

Number of outer-shell electrons.

Electron configuration — role?

Determines an element's chemical properties.

Group 1 metals — trend?

Reactivity increases down the group.

Group 7 halogens — trend?

Reactivity decreases down the group.

Electron shell capacity — pattern?

2, 8, 8, 18, ... electrons.

Ionic compounds — definition?

Compounds formed from positive and negative ions.

Ionic formula — neutrality?

Total positive charge equals total negative charge.

Roman numeral — role?

Indicates metal's positive charge in formulas.

Balancing equations — method?

Adjust coefficients to match atom counts.

Ionic test — purpose?

Identify ions via flame colour or precipitate.

Relative atomic mass — definition?

Weighted average mass of an atom.

Molecular mass — role?

Sum of atomic masses in a molecule.

Ar calculation — isotopic abundance?

Weighted average using isotope percentages.

Mass number — protons and neutrons?

Total protons plus neutrons in nucleus.

Molecular mass — units?

Atomic mass units (amu) or unified atomic mass units.

Chemical equations — definition?

Representations of reactions with symbols and formulas.

Balancing equations — purpose?

To ensure equal atoms of each element on both sides.

Coefficients — role?

Adjust numbers to balance the equation.

Subscripts — function?

Indicate the number of atoms within a molecule.

Unbalanced equation — issue?

Atoms are not equal on both sides.

Group 1 metals — reactivity trend?

Reactivity increases down the group.

Group 7 halogens — reactivity trend?

Reactivity decreases down the group.

Group 1 metals — flame colour?

Lithium: crimson, Sodium: yellow, Potassium: lilac.

Group 7 halogens — physical states at 20°C?

Chlorine: gas, Bromine: liquid, Iodine: solid.

Displacement in Group 7 — example?

More reactive halogen displaces less reactive one, e.g., Cl2 + 2NaBr → Br2 + 2NaCl.

Ionic tests — purpose?

Identify ions via flame and precipitate tests.

Flame colours — lithium?

Crimson red flame.

Flame colours — sodium?

Yellow-orange flame.

Silver nitrate test — halides?

Precipitate forms: Cl- (white), Br- (cream), I- (yellow).

Flame test — potassium?

Lilac flame colour.

Noble gases — definition?

Inert, unreactive Group 0 elements.

Uses of helium?

Lifting gases in balloons and MRI cooling.

Noble gases — reactivity?

Very low, they rarely form compounds.

Argon — common use?

Welding inert atmosphere.

Noble gases — why inert?

Full outer electron shells prevent reactions.